is there any way to maybe put a 24" wheel on my 20" unicycle, like an extender kit for the frame or something? also how much is a nice strong 24" wheel? im basically trying to make my 20" into something light muni rideable :o or, failing that, is there anywhere i can get a nice strong 20" wheelthat would surevive light muni?
In a word, No.
Frames are really cheap anyway, if you’re buying a strong wheelset for muni, a frame isn’t going to make much of a difference.
Yeah, a 24 muni tire would be both to wide and tall to fit in a 20 frame. A muni hub would have larger bearings as well. You really should shop for a whole new uni. You will want your 20 anyway, to learn WW and backwards and stuff. Having a few different unis is the way to go.
In addition to the above, swapping out wheels is a pain.
alright then 
what decent muni can i get cheap? i know more money will get me something better but this isnt going to be reaaalllyyy abused and im a broke 14 year old 
any suggestions, i live in the UK if it makes any difference 
voila:
http://unicycle.uk.com/shop/shopdisplayproduct.asp?catalogid=1089
cheap but with an ISIS hub, not super unbreakable but sturdy, for the weight of a 14 y/o unless you’re doing insane stuff it should hold up well
I you are really broke and pretty small you could probably just get a more aggressive tire for your 20 but if you are not careful it might end up being broke with a broken uni. A proper MUni is not cheap but if you have the coin I would suggest the Nimbus 24" ISIS Muni.
I have tried the whole save money and have two wheels for the same frame thing and John is right it is a pain. My Muni was never ready to go if I randomly decided I wanted to go on a MUni ride and then I would have to switch it back to my road wheel for the daily commute when I was done. I eventually bought a frame so i would just have to switch the seat and post then got got the seat and post then wondered why I didn’t just get a whole uni in the first place, it would have been cheaper than parting one together.