I would think that you should be able to get $1100-$1200 for it.
I too decided to sell a 16" SA58 (railed in my case) and I'm finding the market is stagnant at the moment. Ten years ago, SA58s and STG58s were everywhere. mags were plentiful and cheap too. When I bought mine (a little over a year ago) I drove to every gun shop in a 50 mile radius and nobody had seen a DSA FAL in a long time. I was surprised that not a single shop in the whole Tampa Bay area had an FAL for sale. I wound up buying one on Gunbroker. I bought a bunch of cheap surplus mags online and most of them have jacked up feed lips and require lots of work to make them functional again.
Fast-forward to the present day and Gunbroker isn't very helpful in getting a handle of the market. Very few SA58s are being listed, let alone actually selling. Plenty of kit builds being offered, sure, but it seems that very few people are getting rid of DSA "factory" built guns of any type/configuration. Maybe that's a sign that I should keep it?
I'm thinking that the cost of .308 ammo coupled with higher prices of surplus mags is persuading people to buy low end AR10 type guns instead. It feels like the FAL is somehow getting pushed into obscurity, which is very strange. I guess for most people, the modern day economics of .308 shooting doesn't lend itself to battle rifle blasting and instead focuses on chasing precision, which isn't the battle rifle's forte.