When you pay more for an AK you get 1) better fit and finish, 2) hard to find or rare options like folding stocks, and maybe, if you're lucky, better accuracy. They should all be reliable (except for the new WASR 2s and 3s, and random bad kit builds) and should all have the same general level of accuracy. A hand picked WASR-10 GP can be a fine weapon, if you know what to look for.
With this in mind, find out what you want in an AK. Do you want a folding stock? What kind? Threaded barrel? Bayonet lug? A certain kind of stock? Red dot? Drum mag?
Find out what you really want and go from there. Dont just throw down $600 on something because everyone tells you its 'better'. If you want a red dot and folding stock for example, then a cheaper base gun will allow you to get those things. If you spend all your money on the gun you're going to have an AK with a really good finish, and you're going to be saving pennies and browsing the EE looking at what you can buy next.
My .02