I suppose that depends on what you mean by a Galil conversion.
The Ace/Tromix folding stocks for Saigas have a Galil-type look but are expensive. The Tapco folding stocks are plastic but Tapco makes a matching drop-in Galil-style handguard for Saigas (black or green). Those last two and a Surefire high-cap magazine would be the cheapest way to go, but would still cost as much again as the rifle. The Tapco stocks are not a drop-in fit, however, and require some work.
If you're set on a high-cap conversion, go for it, but I'd just get aun unmodified .223 Saiga with standard or skeleton stock and leave it at that. Personally, I can't see spending more than the rifle cost in the first place just to make it tacticool.