Roma gives the deal for him as being the following (figures in Euros):
Four payments - 5m, 3m, 7m (paid end of June just gone) and 5m due end of next June.
Add-ons:
0.3m every time Liverpool qualify for the Champions' League from 10/11 season to 14/15 season (max possible at time of transfer: 1.5m - now 1.2m heh)
0.25m each time Aquilani reaches the following number of league appearances: 35, 70, 105, 140 (max possible: 1m)
1m should Liverpool win the CL or the league by 13/14 season (max possible: 1m)
Total max cost: 23.5m euros
Total min cost: 20m euros
And then on top of that Roma will get 5% of his next transfer fee.