Mega-tek works wonders for regrowing hair and hoofs. It is expensive, BUT you use such a small amount it actually is very cost effective. Also if you have brittle nails (like me) mega-tek really helps that too ;)
Plus it doesn't smell like bacon grease crossed w/ motor oil and charcoal.
Vida- Mega Tek is AWESOME!! I always keep a bottle of the shampoo and spray for those times we have any kind of fungus. (IT gets bad here in Texas with the swelting heat and humidity) It does seem quite expensive, but I agree with Lola ont his one. You have to use so very little that it's actually very cheap. The only problem with it is that you have to be VERY careful not to put anything else on the problem areas but Mega Tek. It will irritate the skin. After I use it for a couple of days and everything starts to clear up, I switch to my old trusty MTG and go from there. I live a mile from Nasa so our whole life is about Space here. Nasa Astronauts actually use it for a decontaminator when they go and return from space.
Depending on why you need to regrow hair...Horseman's dream works really well on small scrapes, etc. especially on face. My grey Arab scrapes her face occasionally and my vet recommended Horseman's dream and it works really well.