Right up front, I know NOTHING about the the market. The only fender tube amp I owned (a little vibro champ) was as a young teen. I purchased it as a throw in to a deal for a $75 dollar guitar. I foolishly traded it in on some piece of PA gear for very little credit. Not that it was the greatest amp ever, but I really do wish I had it now.
I did a query on reverb.com:
There is a wide variety in prices for various year models. Given that and the ambiguity of what it may be, I'd be inclined to have a decent idea before I put a price on it.
With that said, there's a 1970 clean looking one with EVs at one of the shops listed. They are asking 1250. I generally expect to sell stuff for an asking price about 80% of what a shop would ask. So barring any more information, I'd think an asking price of $1000 might good for a totally uneducated guess.
I just did another search and found this 1972 conversion:
reverb.com/item/643465-1972-fen ... footswitch
They were asking 1100, so that might indicate more like $900 for an asking price.