$400 is pretty much the bottom line for an FAL of any type. The older Century thumbhole stocked guns actually have better parts than the new Century R1A1 pistol grip guns, mainly becauase they used the un-Century marked Imbel receivers and the new guns use Century's own receivers.
You can easily get one of the R1A1's in the $4-500 range. You might get lucky and find one that runs pefectly, or you might have to put $100 worth of parts in it to get it to work.
My most recent FAL is Aussie L1A1 parts on a Century R1A1 receiver which started life as a CEntury guyn, then had almost all of the parts other than the barrel (which was good) and the receiver, replaced. Nice set of American walnut furniture on it, too. I allowed a guy $600 towards a trade he wanted to make me on a couple $K worth of guns. I think that was a good deal for both of us.