Regarding manufacturer sponsorships....
This has evolved quite a bit over the last 5-7 years. The level of offer varies. A few of the biggies (Nike, UA, adidas) offer a fairly substantial deal (not necessarily in $ but in free or heavily discounted gear and free coach and relevant admin gear) to some of the very high profile schools. But where things have really changed is that there is now a brand war and Nike, UA and, to a lesser extent, adidas are partnering with team dealers to try to win the business of each sport at every HS (although, it appears there are pockets of rural areas where this does not apply). If a sports program agrees to buy uniforms and/or team apparel from one of those brands, they get a team discount plus they build credit with the brand that can be spent on select shoes, coach apparel, etc. If a school commits all (or most) sports to that brand, the discount and credit are increased. The team dealer is rewarded with a deeper wholesale discount and becomes more competitive and/or margins are increased. Team dealers who are partnered with one of these brands are often provided spreadsheets that show every single HS in a region with each sport they have listed along with the brand currently being used. Stealing a sport from one of the big 3 competitive brands to another often affords a bigger incentive than re-ordering the same brand or switching from a smaller/cheaper brand. The first time I saw the spreadsheets for Calif., it kinda blew me away.
All this said, they are not giving this stuff away. But, in the current climate, it often allows schools to buy the Nike or UA apparel for roughly the same price as many of the cheaper alternatives they have had to buy in the past.