In connection with USPS's recruitment of Ace in 2004, it was disclosed his base salary was around $600K/year (before, obviously, LA's personal bonus -- now contractual -- upon a TdF victory; before sharing of team earnings). Heras was paid around $1.5M/year, since that was what Saiz had to pay to buy out his remaining year of the USPS contract.
I imagine Ace is now paid more than $600K.
When Victor Hugo Pena was first recruited to USPS, he was paid in the lowish six figures. After two years of the initial contract, Bruyneel cut his salary 35-40%.
Popo, when he was recruited, had several more attractive financial offers from other teams. He got a good salary, but not what other teams were offering him. Bruyneel saw that as a sign Popo was willing to invest in his future, to choose his ideal environment, and as a sign Popo had confidence in the DC program. Of course, Popo sort of brought Bileka with him, so that was another consideration.