Chandler's $10M contract was prohibitive, mostly because the Spurs didn't have the types of contracts to procure him.
If you look at what the Bulls received in return it was:
PJ Brown's expiring $8M contract and young gun JR Smith.
IIRC, Spurs still had Nesterovic on the books but I don't know how attractive his large, long-term contract would've been, and Barry's contract, which would've needed to be paired with another contract in order to make the deal work, also had more than a year on it.
Basically, I don't think the Spurs had the right package of players to get the deal done.
On his contract....it looks much better now than it did when he signed it two years ago and even up to last summer when he was traded. Seems he, Curry, and Nene are actually starting to live up to the expectations that came with their respective teams giving them large deals....but those deals weren't exactly earned at the time they were given.