Im new to this site. some internet nerds might call me a n00b. i got a cheap $80 unicycle a couple of years back and it was a bmx style. when i rode it for a little bit my thighs would burn to the point that it was not good for long distances. i have a 2 mile hike to work and am thinking about getting a uni for the commute. what would be a decent ride for the city that would run no more than $300?
that burning in your thighs is a good thing. it means your wimpy legs are becoming AWESOME. stretch like a yoga teacher and ride that sucker HARD for a day. pop some advil the next day and take 'er off. day after, stretch up and ride hard again. after a week, your shrimpy legs will gain the power of ten thousand suns, and you won’t have that problem anymore.
for the books, I am used to this feeling from riding a bike, but after sitting on a uni, there is no comparison. lance armstrong would probably have sore chickenlegs from a day of unicycle riding. a bike requires a hard ride to give you a workout, but just trying to sit on a unicycle smacks your muscles around harder than a bike.
anyhow, for road commuting, you may want one with a bigger wheel, as I’m guessing you have a 20". you can pick up pretty cheap “trainer” 24 and 26s from the interwebs, but even a mid range uni is in your price range. check out the trading post, tons of sweet deals 
Of course it depends how fast you want to be there… the bigger the faster
Depending on the storage space and other plans to use your toy I would consider something in a range from 26" to 36". I don’t consider 24er a commuter, but still 2 miles are doable on that.
I find my 24x3 to be very good for rides of 5/6 miles. It’s a 24" wheel with a fat, cushy 3" tyre (which makes the effective wheel diameter fairly close to 26").
I do have a 29-er with shorter (125mm) cranks, which is obviously faster: however, i prefer the 24x3 as it’s an easy ride (I can not ride for several months and, when I get on the 24x3 I need no adjustment time and can hop on and idle immediately- the 29-er needs a bit of time to readjust).
Plus, the 24x3 is also good for tackling any little off road bits along the way
For just 2 milles i find any 24" or a 26" to be the best choice, they both are easy to manouver and you can jump over obstacles with ease. I’m on this just 2 months ago, at first, my knees and my legs were so sore, but with a lot of practice the pain disapeared. i use my 24" with 170 mm cranks daily to go to my college on a 2.5 milles trip. i spend abut 25 min. for being in the city and having such a long cranks i think is a good time and i bet you could do it faster.
i have a kh 20 and nimbus 29.
I commute with my 29 from school to apartments 1.7 miles.
Like other people say, you won’t need 29 for 2 miles. A 26 or perhaps a 24 will do.
BUT,
with a 29, you just zipppp ( get to school uphill in less than 15 minutes) and plus its fun for the longer runs too.
I dont think you can go wrong with any of them though.
Get a 26". It is a good option if you are going to have only one unicycle as it will do most things pretty well.
I have both a 24" for muni and a 29" for distance. Normally I ride the 29" 6 miles in the morning. I have ridden the 24 some distance but the extra wheel diameter on the 26 would be best for a commute and the unicycle would not be too big to handle while you are at work.
As you get better and learn to sit on the seat, you will find a 2 mile commute is a pleasure, not work.
If I could only have one unicycle, it would be a 26".
Carey
For 2 miles in the city you don’t want a 36" wheel. Too much of a pain at traffic lights etc. A 26 or 28/29" wheel is probably the best option. A good uni for city commuting can be had for less than $ 300. Others are better than me at giving specific recommendations, if only because I’m in Europe and not all brands are sold both sides of the Atlantic. (I’m assuming you are in the US.)
As to your “burning legs”, that’s has to do with the fact that you are a n00b :). When you are learning to ride, your legs are fighting each other in an attempt to stay on the damn thing. With more experience it is quite possible to ride very relaxed as long as the road is flat, no traffic situations, not too much wind etc.
Welcome to the forum
Hey… you new folks should edit your profiles to show where you’re from… as specific as you’re comfortable.
Personally I would would go with either a 24 or 26" club unicycle from UDC. I have a 24" one and it is a really good value. The only thing I would recommend is switching out the pedals. The stock ones are pretty small. I went with Odyssey Trail Mix metal pedals to better deal with the snow in the winter time because my feet always slipped on the plastic pedals and quite frankly I think I will leave them on. I am able to pedal faster because of the increased grip they provide. However, I am not looking forward to the day my foot slips. Also, depending on the city and its propensity towards theft you will not have that much money lost if it gets stolen.
Yup, and also likely your seat was too low, putting lots of extra stress on your knees and quads.
We don’t know where you are, but here’s my recommendation from Unicycle.com USA:
http://www.unicycle.com/unicycles/cruiser-24-inch/club-24-inch-freestyle-purple/
(choose a color to suit your personal taste). This unicycle is a major bargain, and has a very good seat on it! This is rare in the low price ranges.
I suggest 24" based on flexibility. You can do almost anything with a 24", but as you go larger, it makes it harder to do tricks and other things. If you know you just want to get from A to B, get the Club in 26"; still cheap.
These unicycles have square taper axles. They’ll last forever for normal cruising, but if you start getting into hopping, riding lots of rough terrain, drops, etc., you’ll want a splined axle. Then I recommend this one:
http://www.unicycle.com/unicycles/cruiser-24-inch/nimbus-ii-24-inch-unicycle-with-isis-hub-red.html/
Are there other styles of riding that you are interested in an possibly want to be able to use this uni for?
I have a 20, 24 Muni, and 26. My most fun uni to do my 2.5 mi. commute on is my 24 Muni w/ a road tire & 170 cranks. Riding streight there it takes ~ 25 min & my record is 20, but I usually meander finding challenges along the way (what I like to call urban Muni) taking close to an hour.
A 24 would be good for also doing teck Muni, tricks or trials. A 26 would be good for moderat Muni. A 29 would be good for XC Muni & medium road rides, but prob can’t bing inside public transit. I think 36 would be too big and cumbersome for commuting through traffic and you prob could not fit it on the front racks of busses.
A uni that’s also used for Muni, trials, and jumping off stuff needs to have a splined hub. Nimbus sells unis right around your stated $ limit @ 300-320. Also check the used section hear for used unis for less than that.