Please consider looking in to the accredited investor designation. While 1 Million net worth or 200K-300K in income is a good definition by the SEC it limits the amount of people who can invest in a start-up. Why not have it be a % of your net worth or income that you can invest. For example if you have a liquid net worth of 200K allow the investor to invest up to 10% or 20K. California has a rule that could be applied to all of the US:
The investor has a minimum net worth of two hundred fifty thousand dollars ($250,000) and had, during the immediately preceding tax year, gross income in excess of one hundred thousand dollars ($100,000) and reasonably expects gross income in excess of one hundred thousand dollars ($100,000) during the current tax year or (ii) has a minimum net worth of five hundred thousand dollars ($500,000). "Net worth" shall be determined exclusive of home, home furnishings, and automobiles. Other assets included in the computation of net worth may be valued at fair market value.