$400 is a bit high, but if it's at a gun shop, I wouldn't turn it down.
I bought a GP-WASR-10 a while back and paid $375 for it.
If you buy a WASR, BUY IT IN PERSON. Yes, you can order them on the 'net cheaper, but are MUCH more likely to buy a turd.
Consider WASRs to be kit guns that the riveting has been done for you.
Buy in person and check for: front sight block cant, gas block cant, magazine fit. If the magazines are tight, but still go in, this is ideal. The guys at Century do not deburr the magazine well when they mill them out for double stack magazines. You'll have to do that yourself (take a mill flat, or a flat smooth file and s-l-o-w-l-y remove the burrs). If those things are OK, then you'll have a rifle as good and reliable as any other AK.
Look on the left side of the trigger, if it says Tapco G2 on it, you're good to go, if not, go to tapco.com and get the G2/retainer plate package for $46, it's worth it. Many of the newer WASR imports already have the G2 in it, if that's the case, then just buy the retainer plate (replaces the shepherd's hook). Again, it's worth it.
IMO stay away from the "AK-STG-2000-C Romanian STG-2000C 7.62x39 Rifle" in the second AIM link above. They charge $70 more for cheap, crappy furniture on a WASR (look at the receiver, no dimples, it's a WASR). For $4 go to Ace hardware and get the stain of your choice and a cheap brush, and give the laminated wood 5-7 coats of stain.
If you can still find them, the Yugoslavian AKs are a bit better and have been better builds from Century, and they run about $100 more, but are getting hard to find.
Are there better AKs? Sure, but not in that price range of the WASR (SARs are getting pricey as well).