I'd maybe add Ekpe Udoh. Potential for shotblocking next to Cousins, but couldn't even make a go of it with the Bucks, which says a lot. I do remember hearing somewhere that Malone liked him from his Golden State days, though, so you never know.
Well Udoh is probably more obtainable than most. I've always liked him, and thought he was on the right track with the Warriors. But since then, he's had a hard time getting consistent minutes. Especially with the Bucks. Just too many PF's on the roster.
Sanders: 25 mpg and 1.7 blocks per game
Henson: 26 mpg and 1.7 blocks per game
Udoh: 19 mpg and 1.0 blocks per game
Llyasova: 27 mpg and 0.1 blocks per game
Adrien: 25 mpg and 0.8 blocks per game
Thats a lot of players getting minutes. Udoh would probably be an upgrade as far as shotblocking goes, but not sure just how much. Udoh's first two years with the Warriors he averaged around 1.7 blocks a game in around 25 mpg. Going on memory here, so I could be off a bit, but he did show natural shotblocking ability.
My first choice would be Ed Davis, but if the Grizz are thinking of dumping Randolph, then Davis is probably untouchable.