I like the convenience of mail order. Being able to order exactly what I want, and knowing when it will be there, and having some control to rush it there if I really want. My track is far away, so ordering things through them would require me to wait until the next club race (hopefully) for it to show up, which means I'd have to wait another week before I could try it out. Having stuff sent to my home means I can get it several days before the next club race, and try it out sooner. I don't really care about a few bucks saved here or there, it's all about convenience to me.
So, I try to find other ways to help my club. I did a bunch of programming and web design to build them a very nice custom site (with some awesome graphics help from another racer.) All that custom code would cost them a mint otherwise, but I did it for free. If they charged twice as much for racing, I'd gladly pay it. If they had a membership that I could pay dues to get some kind of special treatment, I'd happily pay that, too. I absolutely will support my track as best I can, but I don't want to give up the convenience of having things delivered to me on my agenda. I also make a point to buy as many consumables (bodies, traction compound, motor spray, etc) from the local track as well, since I don't need those things in any hurry, usually.
If my track were closer, it wouldn't matter as much, but even then, I'd still prefer to handle my own ordering given the choice. Since I only make it out once a week, waiting a whole week (or more, if I miss a night) to complete my latest loot cycle would be tedious to the point of madness.