Wal-Mart, really? Hmm. At the college level, I guess they register trademarks, etc. such that Wal-Mart can't, without paying royalties.
meganchi, is all the apparel the same? It would be nice if you could divide up t-shirts, hats, sweatshirts, etc., one item per group, and they get all the revenue -- assuming the t-shirts don't say "X School Choir." But you might have better success if you can show the financial benefit of larger orders -- eg, you get a lower price per shirt for an order of 48 rather than four orders of 12.
Maybe you could get most things in a generic "X school" design, but then do t-shirts specific for each club that participates, and then divide the revenue according to the number of t-shirts for the clubs (if football sells 10 in a quarter and choir 5, then football gets 2x the share of profits). You might be able to get the t-shirt shop to give you a reduced set-up charge if you print a bunch of generic t-shirts with the school name, and then use a second color for the club name (rather than separate orders of a 2-color design).
Sorry, I don't have any easy answers. We run into the same issue. Plus, now Walmart carries T-shirts and some other spirit wear with the logos of our local high schools.
I am on our PTO board. We have our own apparel merchandise that is sold throughout the year at games (we reserve our own table, but often times other groups take them over to sell their apparel). The problem is, our school has choir, track, football, etc. selling apparel but we are stepping on each other's toes. Has anyone had experience with how to go about splitting the proceeds between all groups so that we can all work together to accomplish the same goal?