Will:
I'm unclear on a point-what's the difference between buying a repro and making one yourself? The cost? Either way, it's a reproduction. Originals are very rare and sometimes difficult to authenticate.
SOGD is selling repros for $350-ish, but you'll need a mount. If you shop around you *may* find someone selling them with the correct mount.
If you add up the cost of all the parts & a rifle, and a realistic fund for gunsmithing, it'll be really close. If you're looking for a $150-$200 91/30 sniper look-alike with all original parts, you won't find one. $400 seems to be the baseline for correct repro sniper.
IO's sniper for $398 is the cheapest repro that's very close to original, and has correct (but repro) parts.