Blending many years of racing, having worked throughout college at racetracks a decade ago, and my current situation working as an Economist, I think the points I'd like to make are as follows.
1) An indoor track will almost never support the track itself revenue wise. Entry fees will not cover the square footage being used by the track, the electricity being burned in the pits, water and track prep expense, and so on. Any attempt to make it do so will leave you priced out of the market. The track exists to drive revenue to your shop.
You want practice fees to be cheap so kids come in on weekdays during the summer and strip the gearboxes in their Traxxas' and so on (sounds cruel but it is true!). You want race fees to encourage a large turnout so said racers will buy tires.
As has been mentioned, margins are tight so volume is your only way to survive. Your revenue projections need to show the track in the red. To again somewhat echo the poster right above me, you need to be a hobby shop with a track, not a track with a store.
2) Research your market carefully! If you're in CA and 60 miles away from an existing indoor track, my best guess is that you're 60 miles away from a viable market place knowing where most of the indoor tracks in CA are currently located. Or, you're in the Bay Area where the odds of you finding a building wherein you'll be able to cover rent even with 100% of your gross revenue is thin. An indoor track needs either affluent customers or low overhead and those two work with an inverse correlation geographically.
You were smart to not post a specific area yet though or the thread would then be filled with people saying "do it" who will then only race once a month at your place and never buy anything there anyway.
3) I've been a "regular" at about a dozen indoor tracks in my life. At over half, the owner worked a "day job" while trying to make the track break even while dreaming of profits.
4) Get something like the Hobbytown USA franchisee prospectus. It'll give you a realistic idea of what a shop alone is looking at making.
5) Plan on selling your parts/etc. at prices competitive with the online stores. I've seen way too many hobby shops get stuck on having to have a certain % markup on each item. It's better to sell two sets of tires that cost you $17 each for $20 to match a .coms' price than insist on selling them at $22 and maybe sell one set and incorporate that into your revenue projections.
6) Re-read #2
Good luck!