I've seen this come up a few times. We paid far too much for ours in '04 (close to $3k), but we still have it. We did put a Costco topper on it a few years ago for additional padding.
The pump still works, but the LCD numbers on the remotes are long gone (no clue if they're replaceable - don't care). It's just a guessing game now, but to be honest, we rarely change the pressure.
We went through a couple other mattresses before this one. As overpriced as they are, it really helped me with night time hip and shoulder pain.