When you say "Cheap - Real cheap" (which, incidentally reminds me of "Guns - Lots of guns" from "The Matrix" - but I digress) I'm thinking that you might be best off just getting a "real cheap" ($200?) integrated amp with a S/PDIF input.
Of the plethora of D/A converters out there, you aren't going to get cheaper than something along those lines.
Now, if I'm wrong and "Cheap - Real cheap" means $600, 700, $1000 (which is cheap for a nice set of converters) then let me know...