If you have any mechanical knowledge and some fairly basic hand tools, you can convert it yourself. I've done 2 so far, both .223's. I have less than $100 in each one as far as parts cost. G2 fire control group, stock, pistol grip with screw and nut. The bullet guide kits run around $25 or 30, but I made my own from a piece of 1/2" steel pipe.
I will be starting on converting my Saiga 12 in the next few weeks if I get time. It involves a bit more work(no holes for the pistol grip nut, etc.) but it's still nothing that is beyond most people's abilities.
Check out Saiga12.com for lots of great info on conversions and other tips/tricks.
I'm no expert, but if you have any questions, let me know.