The photos on your posted link are tiny. Pretty hard to judge them when they are 200x300. The ones I did look at were too far away from the subject or they were photos of people's backs or walking around. Or there were 7-8 of the same person with the same pose. Boring. Also, learn to like auto focus. Rely on the tools you have.
You want to make money at the local field on paintball photography? Take good photos and immediately show them off. Bring a laptop and let people see them. Bring a few pricelists and have the people pay up front with the expectation that they will be available the following week (or what ever time you choose) at the field. Or charge them a couple bucks more for mailing them.
Or...do the same as above but instead of making them wait, bring out a printer and print on the spot. This requires that your your photos are spot on and you have good printing equipment. You can't spend time correcting the photos. Print a few, show them off to players and parents and the money will be thrown at you.
Or...set up a website that sells the photos for you. This requires volume selling for you to make money. The downside is that you're paying for a site to manage your sales and it also requires people to go to the site, pick out photos, and pay form them. It also requires you to cull through your photos so that people don't get bored or confused when picking out photos. The upside is that you can spend a little more time cleaning up photos prior to uploading and your collections can be easily managed and organized.
Pricing? That's dependent on your market. As somene else mentioned, paintball players are generally cheap. They are also impatient. Not a good combination to make money.