Stay away from the WASR series. They are the bottom of the barrel AKs. I have more AKs that I know what to do with and love the series.
I currently have about 6 built one and about 14 more kits to build (waiting on receivers).
The only really good Century AKs that I have seen are the Yugos. They are wide trunnions and are beefier and heavier than the SAR and WASR series of guns that Century builds.
The WASR series are the cheapest but they just lack the finish that the more expensive models have.
If I was looking to get a cheap AK, I would look at
http://www.classicarms.us and look at the Saigas. They are real russian AKs built at the Izumth (sp?) plant and are as real soviet as you can get.
However they are sporterized versions so you don't get the cool pistol grip and other AK style aspects but they are quite convertible to that style (but you need to keep 922c in mind).
I really enjoy the whole AK series because of how "evil" they are perceived by the public even though they are nothing different than a Ruger 10/22 that shoots a bigger round.
Any AK should be a decent 100 yard rifle. They were never designed to be long distance rifles, they were designed for close combat/room to room combat situations so long distance accuracy was never ALL that important compared to the AR series which out of the box are much more accurate.
Funny thing, I shoot my AKs MUCH more than my ARs. Ammo by the case is still reasonably priced (150-200 a case but going up) compared to 250-350 a case for .223.
My favorite AK is my Yugo underfolder. A lot of fun to shoot. Yes, you can get much more accurate surplus weapons an for cheaper (the Mosin series anyone?) but they aren't semi automatic or have ammo that costs much more.
I have been looking at the Swiss K31 and its a very lovely gun however ammo is very pricey. Then you get into the 308 models where ammois REALLY pricey.
Thats why I stay away from the CETMEs and the G3s and other 308 guns. Just too expensive to shoot these days.
Don't get me wrong, they are awesome guns, I just choose a lot of my guns on the availability and price of ammo. What good is a gun if you can't afford to shoot it?
I also don't care for the G3 (I think its the G3 series) because of the fluted chambers.
A fluted chamber will aid in extraction however since its fluted, when you shoot it, it destroys the brass making it totally unreloadable.
If you really want an AK, get a Saiga first then followed by the Yugo series and then lastly the WASR series (those are the cheaper ones). If you can afford an Arsenal or other higher end brand, go for it, I'm mainly concerned with the lower end AK series.
I would love a FAL one of these days, I love how they are built.