It’s hard to imagine a less useful uni for the riding I do, but I want a 26" Conundrum anyway. If you have one you’re interested in selling, let me know. Frame alone or whole uni.
Prefer PM.
Hi,
as it is no longer produced, it might be a harder to find/more expensive solution compared to other frames.
You can read this earlier thread discussing the possible solutions for a fat Muni.
If you have any questions, just ask 
This place claims to have the frame for $260, but who knows.
http://www.hfutmpa.com/product_SURLY-CONUNDRUM-UNICYCLE-FRAME-ONLY.html
The “buy now” link redirects to Jenson USA with a 404 page.
Seems like another online shop that hasn’t updated their listing to reflect the discontinuation. 
Thanks for those suggestions. It’s definitely not the most practical pursuit, but if we were practical folks, there’s a good chance we wouldn’t be unicyclists.