Hard to pin down a price. If it's a skeet gun with the upgraded wood, my SWEG would be under $500, more than $300.
Do you intend to collect, shoot or use it as trading material?
Like Model 12s, etc, 11-48s come and go as fashion ebbs and waxes. I've seen a coupla 20 gauges on the SC courses. 410s usually run a bit less than a gauged gun.
The grapevine has it that the 11-48s were dirt sensitive. I dont see why, their action has some parts in common with the 11,a notoriously reliable arm. Good cleaning and lubing should (fingers crossed) keep it perking along.
Good luck, it should be fun on the range...
BTW, last I looked, Gunpartscorp had stocks and other parts....