I've been wondering about this a bit too. I've done some research around the dog photographers (which I imagine to be similar to horse events, or the sports ones that do kids carnivals and the like). It seems the going rate for a hi res file is only around $10 with various minimums, or 1 or 3 to 5 or so. One I found asks $50 per file.
There are a tonne of them going to events often not even as official photographers for the event just taking thousands of photos and posting them on their website or facebook and trying to sell them. Most of their photos are very ordinary I might add, not work that I would ever put on public display. I just wonder how much these people sell at $10 each and whether it is worthwhile.
That method isn't for me, I'm thinking of heading more towards individual clients and jobs. I'm not sure what I'll do, just taking my time, learning as much as I can and sussing out threads like this to learn where to pitch myself in the future. I'd appreciate any thoughts!??