Sounds expensive for old tech. I wouldn’t touch it personally unless it was a give-a-way price. The Tarmac SL6 is more aero than the old Venge. And yes, there are huge differences with the 2019/2020 Venge.
If you live in a hilly area, why do you want a stiff aero bike? Once again, you’d be better off with a Tarmac IMO.
I think the old Venge might be a great crit bike. I bet if you waved $1000 cash in front of the shop owner’s nose, they might take it. It’s been sitting there for 5 years now.
You should also look on ebay. I see that whole bikes have sold in the $2000 range.