As far as the CETME goes, it is a good gun for the price. It uses HK91 mags and it made on a Stainless Rcvr. Probable one of the better Century products out there right now. I have one I got from Impact and it is a good shooter. The only problems I have seen is the front site. Some of the assemblies were put together with the front site canted, making it hard if not impossible to get sited in. If you buy your CETME from AIM surplus and it has a problem, they will make it right. I like these guns, they shoot nice and will munch up any kind of Ammo. Mine is pretty darn accurate. They are also made from new kits, surplus Spanish military rifles, not used ones like most of the G-3 clones out there.
FAL's on the other hand, IMHO, are a superior rifle(design) in all aspects. Easy to strip and clean. Adjustable gas system to compensate for fouling or different ammo loads on the fly. They are rock solid, you can get 20rd mags for 8 dollars all over the place. Spares are readily available for all parts of the rifle from more places than you can bookmark.....The Century ones are a crap shoot as stated. Your options are(there may be more, these are the most obvious):
1. Century FAL- Hit and miss for 500 bucks. As stated above, you could buy one maybe get lucky and be ready to go or need to send it off to ARS for an additional 300 bucks to make it right.
2. Buy a parts kit, Imbel rcvr and have one custom built by ARS or others as mentioned. This method you know you will have a good shooting rifle. Need a good kit, not to hard to find. There are places that sell kit anywhere from 150-250 bucks, another 200-220 for a Imbel rcvr and about 350 for the build including finishing of the rifle....lets say 770 bucks. Or you can assemble yourself if you are profficient and save the assembly dollars.
3. Buy a "Kit" gun from DSA. These are built of of Austrian kits and are superb rifles. Good shooters, well made and come with a limited lifetime warranty. This is the route I went as many others have too.......
4. Follow the auction boards. There are always a crap load of FAL's on
http://www.gunbroker.com and you can get a rifle for a decent price sometimes.
Buy a IAI M444. These are suppose to be pretty good, but they have some small problems I've read about but overall have gotten good reviews.
Bottom line, I would go for the FAL over the HK copy unless you really like the HK style and then I would buy the CETME.For 500 bucks in the Main Battle Rifle world you get what you pay for. I would hold out till I could get 700-800 dollars and get a good FAL that will last you a lifetime and will be a rifle you will love to shoot...