Make a plan.
Costs:
1.) Cost of Land (buy or Lease)
2.) Check with county and city about zoning, permits, noise pollution laws
2.) Yearly Taxes on Land
3.) Liability Ins.
4.) Needed Equipment (Tractor, bull dozer, water)
5.) Frustrations, mean people, Personal finance risk
6.) Personal time.
7.) Hiring help.
Income:
1.) Advertising dollars. Check with local MX shops about sponsorship, sign placement.
2.) Calculate how many riders at $10 dollars a bike you would need to break even every month.
3.) Satisfaction, Fun, Friendships. These are pluses that are hard to measure.
I wish you luck and if you get something up and going post it on DRN.