AEG was £6.75m and would easily fetch £8-10m in Europe now. Aside from the overarching view of him among villa supporters, the fact is that he got 4 goals and 4 assists in 34 PL games last season, is still only 25 and was actually in the top 20 players in terms of stats for european wingers under 25 across the top leagues.
Jota cost £4m and would be unlikely to go for that sort of money now as he was peripheral last season. I would see him as a makeweight in a deal with a championship club if we are doing business with them.
Trezeguet I would certainly give one more season as he showed enough and actually arguably kept us up with his goals...
Samatta, we might be inclined to keep him for one more season as he's only just got here but I could certainly envisage a loan with option to buy somewhere like Turkey or France to be honest.
If we were to sell them all there is definitely 15-20m in that lot if we played to their stats and strong points from the season.