May 2007 issue of Shutterbug magazine has an article about starting a sports photo business, what's needed to make decent money at it, etc. You might be able to find a copy of it archived on their website. They estimated startup costs of $7500 to "tens of thousands of dollars". At the low end, it's for basic camera and computer equipment, some of which you might already have.
As part of those startup costs they heavily emphasize one point that I have found to be quite true myself... To be successful you must do at least minimal on-site printing. Impulse buyers are a big part of your customer base, and if you don't print on-site, you lose them almost entirely. I'd have to estimate that you can expect to only make half of your true potential, if you don't offer on-site printing and capture those impulse buyers in the heat of the moment.
The startup cost projection does not include wages to pay individuals to do the printing and sales on-site. That's another consideration. It is more expensive to do on-site sales. A lot more expensive, between equipment, set up time and especially wages you'll need to pay to get the job done (perhaps it could be structured as profit sharing that would also serve as a sales incentive, maybe something simple like $1 per print sold, rather than a straight $x.xx per hour pay rate).
Another thing I've found in my own business is that you must think in terms of leveraging your shooting to create other revenue streams from it. Fact is, people today have less disposable income for luxuries like commemorative prints than they did a year or two ago... Blame the economy and the rapid rise in the cost of some of the real essentials in our lives. Fuels, food, etc. come first, and are tapping people's budgets harder than ever before. So, they are spending less on luxury items where they have a choice. It's clearly effected my own sales. Single day events I shot in Fall 2006 that netted me $1500 in online sales appear to have only netted roughly half that in 2007, and we'll just have to see what they're worth this year, since people are feeling the pinch even more now.
One solution I can see is to find other ways to sell the same photos, since I can only be in one place shooting at a time. I've been making and selling some fine art prints of select images. Whenever possible and appropriate, I'd sell them for editorial usage. I'm getting more model releases, that in turn will allow me to use some of the same images in more commercial ways.
You do need to carefully evaluate your own, local market for potential. Look for competition and any exclusive deals they might have that prevent you from shooting commercially at their venues (note that there may also be potential partnership or "2nd shooter" deals here, if others are already doing this sort of thing in your area, which can greatly reduce your own startup costs). Try to estimate your true customer base and how much they might have available and be willing to spend. Think creatively about ways to market and promote yourself and your services, as well as alternative potential uses for the same services (club shooting, as suggested, is one idea... but watch out for greedy club owners who want a big share of your profits!).
We'll all be waiting anxiously to hear if Lance makes it out okay! 
