Since "What does maintenance and training cost?" is the most popular post of the blog, I think anyone who reads it should also read the article at
which breaks down the "day rate", or trainer's daily fee per horse, to show where that money goes. I think new owners sometimes assume that all or most of it goes in the trainer's pocket, but it's actually used to pay all stable employees and all feed for the horses (plus a lot of other business expenses) - employees and feed are the two biggest expenses a stable has.
That means if a trainer is only charging $65/day in a public stable of claiming horses in 2012, the business is not viable unless it has some kind of outside investment.