Hard to find them with original barrels. What would I expect to pay for an original barreled 74 with fixed stock?
not long ago you could find them for around 300 bucks, today they are almost double that, wish I had bought several when the price was cheap and then sell them today!!
Well Centerfiresystems.com has them for $599.99 already built. Not sure where to get kits or what one would cost but I'm afraid it would be close to that or more. For a moment the kits were available for around $250 but I think Century bought up all those (or perhaps they are the ones importing them). I know Century has a mixed history but with two in our build group buying the Century Bulgarian AK 74 the time I built mine I have to say they beat me in price and the finish on those is rather good as well. The down side, in my humble opinion (gotta tell myself they didn't get the better deal), is that the plastic furniture that came with them melts after about 2 mags worth of rounds. Most picked up some wood furniture (my kit came with original synthetic furniture which I gave to my dad since I prefer wood) for around $25 (doubt you'll find it that cheap now).

What type of finished build are you looking for? Cloned Russian? Back to a near original Bulgy? I picked up a Bulgy kit without a barrel from Atlantic Firearms which arrived today, for $185. It came with plum furniture (except for the crappy brown plastic handguard). If you are planning to just have it built without any special "authenticity" cloning done, then just buy a new rifle. Like USCombatDiver said, a good build will likely cost you the same if not more, than buying a new one.
Kits with original barrels from what I have seen lately are going in the $350-$400 range. Or you can check out what-a-country or ak-builder for their kits. They have bulgarian barrels in the $299-$330 range.
If you decide a kit is the way to go, just keep an eye out for deals. Just scored a 74 kit last week with the original barrel and an extra bulgarian barrel, along with some virgin east german furniture for $275.