I don't think the imports are playing on minimum dollars, but I don't think they are being paid in line with their production - Martin-aside, who I'm sure is on A-level import money (below say, Cotton, in line with Patterson et al). Clark would be on probably half of what he deserves, and I imagine Adams also (although more than Clark). I believe Adams' motivation was to play for coach Buford and try and follow Tate's path to the NBA, which I believe will happen - there is no way in hell he is in the NBL next season. Clark again didn't play for two years. I'm sure he earnt good money in China, but again, he hasn't played in years. He could have quite easily stepped on the court completely out of shape and been a dud. It was a risk.
$250k for Cooks I'd believe, and performance wise he should be around the $400k mark based on production. I believe he will get an NBA shot this offseason in any case, but it will be a significant bump if he stays.
DJ I'm sure the Kings offered more than the competition (returning player from a big college), but I doubt very much he is being paid in line with his production either. He will probably get close to 2x what he is on currently in the NBL, assuming he doesn't look overseas (which I feel is a strong chance).