If you're looking for a high school camp for purely self-improvement, the Palmetto Basketball Officials Camp in York, SC is a good one for a small price. The website hasn't put up its 2015 information yet, but here is last year's information.
http://www.district3hoops.com/camps/York%202014.pdf
If you're trying to be seen by college assignors, I
think Presbyterian College in Clinton, SC puts on an officials' camp at its Camp of Champions, but don't hold me to that.