Individual sponsorship is really difficult to get at low divisional levels, so you can either do as I have said above or you can go for team sponsorships. I know a lot of pb stores will gives discounts if a team/group buys a large amount of gear at the same time, thats something you can look for that will downsize your costs. 

getting into actual sponsorships can be difficult. Your team/organization requires a lot of things for a company to think you would be a good candidate to sponsor. If you do have these things there looking for (brand loyalty, good sportsmanship, maybe some tourney wins, good exposure, etc) they will most likely start with some discounts. I know a local team around here had a deal with angel paintball sports where they could have done up A1 flies, complete barrel kits, tanks, and pretty much their full line of soft/hard goods all for less than what the marker retails for. 

Getting free gear is really difficult, and should NOT be expected or asked for unless your some of the best/nicest players in a league that draws large crowds and is most likely televised.  If your at this level, you shouldnt need to ask how to get sponsorship.