The MHDT Labs
http://www.mhdtlab.com/ Orchid is an R2R/tube DAC that a few folks here have and think very highly of. One or two of them not only tube-roll, but have gone to the effort of cap-rolling, as well. They also offer other models, all the way up to a fully balanced R2R/tube model that slightly exceeds your budget.
Like MHDT Labs, Denafrips makes R2R DACs, though I do not recall if they use tube(s). In the review of a couple of their models in a fairly recent "Stereophile" the Denafrips models were compared to a 3rd R2R DAC, whose mfgr/model I've forgotten. Easy enough to search the Stereophile archives online if interested. Do recall that both companies, like MHDT, offer a few different DACs.