I've had shares in a few through Harry Lawton and that much touted 'colourful character' Wayne Beavis through Celebrity Thoroughbreds.
I think you tend to pay through the nose for horses rejected by the big boys (Inghams etc) who (I believe it is probable) get first whiff of anything that is any good.
All of the ones I had shares in had very few starts before breaking down. The Celebrity nag didn't even make it to the track and as they were going bust they still billed me for a 'special levy' of $600 (which I didn't pay).
I'd be inclined to leave the purchasing to those who are part of the 'network' (right school helps but nouveau riche accepted as long as they have dollops of cash).
Pardon my cynicysm and paranoia.