The concept sounds very similar to the Community Supported Agriculture (CSA) model where the grower sells shares of the forthcoming year's harvest. The 'investor' pays the grower a fixed amount in advance of the growing season to secure a share of that year's harvest, safe in the knowledge that they will get a weekly supply of very fresh veg/fruit etc and happy knowing that they are supporting that local grower by easing his/her cashflow.
It's also a way to share the risk/reward, so that if a harvest fails, both the grower and the consumer suffer, rather than just the grower. There is usually also an option to pay a fixed amount on a monthly basis, which in total works out slightly pricier than the lump sum at the start of the year. CSA members are also encouraged to put in a few hours of work on the farm on a voluntary/unpaid basis. That gives them the chance to connect closely with where their food comes from. There is a good outline of the CSA concept here. This is something that Tiny Farm does, in conjunction with selling at the farmers' market.
It's obviously a win-win model and I know it's becoming quite popular over here in the UK. It's something I want to implement when I get started next year, however I am wondering, in practical terms, how easy a CSA is to set up in Year 1 (or even if it's possible at all). Unless you already personally know all your potential local CSA-ers, how would you go about persuading strangers to sign up? You're asking them for a not insubstantial sum of money on the promise that they'll receive something (IF all goes well) in the future and since it's Year 1, you have no proof that you can actually produce anything!
Perhaps a CSA is really only feasible from Year 2 onwards…and maybe a weekly box scheme is more approriate (plus farmers' market) in the first year. At least with a box scheme, the buyer knows that they only pay if something is actually delivered. If, as a grower, you're able to prove your capabilities in Year 1 via a box scheme, then perhaps in Year 2 and onwards you can transition your regular customers into a CSA.
I would love to know what Mike's (and anyone else's) practical experience has been with this issue…