Re: Cetme .308 vs Century ar15
Like people have already said...Century rifles (CETME's and otherwise) are a love/hate relationship. I have seen some that ran okay while others looked like they were assembled by a blind monkey after a two-day bender!
CETME's will fetch around $500 depending on everything included like mags, scopes, mounts any upgrades, etc. Century C-15 A2 rifles are fetching around $700 (again, depending on options/accessories/etc.). Keep this in mind if you are considering an "even trade" for the CETME.
It really comes down to what you want, but if I were you and considering this trade, I would want the opportunity to both carefully inspect the rifle and to run some ammo downrange with the CETME because while some functioned okay, others were just jam-o-matics! Also, look over the welds on the CETME and see how they are made (if they are smooth or rough/uneven). Some are sloppy as hell and are evidence of the complete lack of attention to detail. Take a close look in the barrel for signs of it being shot out or pitted. Get a metric feeler gauge and check the bolt gap (in short...the headspace) of the rifle as some were not even close to being within spec. (I can explain this process in a PM if you want the info...I won't waste space posting it here).
Anyway...that should get you started on thinking about this trade a little more. Give a shout if you need anything else.