seen it i think on this site:
http://www.banskoski.com
if you go onto the Prices section, then it has an option for equipment hire etc... hope it works.
hired board and boots last year it only cost 50lev for 6 day's.
when you get to Bansko walk to the end of the main street as you turn right to walk to the lift station you will see a wooden shack on your left, try them.