I have to ask, where can I find a pot like this??
I would need it to be 18 to 21 inches to look like the one you have here. there just isn't a lot available online in that size range unless I just don't know where to look
A number of potters in the U.S. can make you one that sized, or you can find an imported example. That size range isn't all that rare. It's just a matter of looking around. Nao and Waldo St. have been mentioned. They both do great work in larger pots.
Other sources are online. If you're not on Facebook, you're missing out on a lot container-wise. There are entire groups devoted to selling and buying bonsai pots, which includes some of the premier makers in the U.S. "Bonsai Auctions" "Bonsai pot auctions" are two of the largest. There are literally hundreds of pots offered up on those sites every month--some pots are crap, others are terrific.
If you want a more refined imported Japanese pot, check out
Matt Ouwinga's ebay pages. He carries alot of shohin sized pots (which can be EXTREMELY expensive), but he also has a wide range of less-expensive excellent imported Japanese pots in the size range you're after.