I'd say 50.00 to 75.00...
Value will go up when it turns 30 years old...you have an 85/86/87 year model.
This frame is very UNLIKELY to crack at the BB...so ride it...enjoy it...
What is frustrating about trying to get a GOOD 1980s Modelo 850/1000/1500/2000/3000 is that they are made in Italy - and almost always reside in Europe. I.e., they'll show up on eBay International and the shipping will kill you. The day I set foot in Europe for a future vacation - I'm sure you'll hear about me on BBC news regarding a bicycle mugging...with the victim losing a Benotto...(yep...that'll be my 15 minutes of shame...)
Almost all Modelo 850/1000/1500/2000/3000 here in the North American continent already - are - made - in - Mexico - i.e., they will be cheap to buy, and cheap to ship - BUT WILL BREAK...
To buy a North American locale Benotto 850/1000/1500/2000/3000 that will not likely crack means you have to buy a 1970s thru 1980/1981 bike.
Of course, if you are lucky as is one member here...you'll have an opportunity some day to buy a Modelo 5000 in Gilco/MS tubing...very pretty...but not cheap either. Made in Italy of course...
=8-)