We cater here in Houston. I know this is not hot dog country so I keep my prices a little lower than yours. Barbeque is the preferred food catering item here so my prices are higher for that. Use the catering prices that are pretty much inline with other caterers in your area. I called several and looked at their web site prices before bidding on a catering jobs.
If the "all you can eat" concept works for the hot dog then very cool because the net profit is along the lines of a fair/event. This is creative and I am curious how many folks will opt for this.
We do the combo for a small or large hot dog and there is around a 1.00 price difference, use the small chips and canned drinks.
Sounds like your a good planner and will be competitive for the Bowling Green area.