I guess where the confusion is coming in is what you consider a "good" FAL. The only FAL's that I have seen that shoot what I consider decent, didnt cost $5-600, more like $1500 and up. Two of my FAL's were early kit guns, but not made by Century, I dont know who put them together, but at the time, I just had to have them as I thought they were the scheisse, but I'm VERY happy they are gone now. They cost me $500 each then and I dumped a ton of time and money into them trying to get them to work right. They never did, and forget about any kind of groups when they did get through a mag. I also had a FN rifle, that worked flawlessly, but it too would not shoot a group to save its arsch. They all "strung" their rounds, especially when the gun got hot. I did like the FAL's ergonomics, but compared to the AK's and AR's, they are heavy, and slow and really dont shoot all that much better when they do shoot. As for AK accuracy, I have a Krebs AK103K($700) that will shoot around 2" at 100 yards on a regular basis. My WASR10($360) will shoot 3-4". Thats better than even my FN would do. Will a $700 AK shoot as well as a $700 FAL? I'd be willing to bet they are pretty close. If your going to compare things, compare apples to apples.
Building a gun can be fun and save you some money, but dont think its going to work or shoot great the first time out. If it does, I'd say it was a miracle. They can also EXTREMELY frustrating and consume lots of your time, ammo, and money. If I was to get one put together, I would most certainly get a gunsmith with a GOOD rep for that type gun to do it, but I'll guarantee you, it wont cost you $5-600 for the total gun. When it comes to getting a gun that you want, your going to pay for it, one way or another.
If and when things are lifted, I will either get, or have someone like Krebs put as true an AK103 as possible together for me. I think the Russian rifles are probably the best, and at the very least, a barreled Russian receiver, made and assembled there is the best place to start. I like the full, solid polymer folding stock that these rifles come with over the others available on some of the other guns. The AK74 type brake works very well and you can tell the difference right away between guns that have one and guns that dont.