Freeman that koa reso you built is beautiful.
Anyway, this thread is a few days old, and the OP may have already made up his mind, but I'd like to chime in on the subject. I own a National M2, which is a wood-bodied, single-cone, round-neck resonator guitar. My brother owns an Epiphone Biscuit, which is essentially a much cheaper version of the same guitar. Having played both, I think the Epiphone is pretty good for the money. (It only cost about $300.) It appears that Epiphone has stopped making this model, which is a shame. If you can find one then I recommend looking into it.
As far as other inexpensive resos, I would look into Busker Guitars in the UK. They are more medium-priced than "cheap," but at least the exchange rate between US Dollars and British Pounds is not quite so bad as it was a few years ago. Honestly I don't know if they even ship to the U.S., but any company that makes a recreation of this old art deco National design must be worth investigating:
http://www.buskerguitars.co.uk/shop/page/12?shop_param=