I definitely think it is a very good idea! It is a very lucrative business if you sell a high quality hair because you'll have excellent reviews and repeat customers. You make more when you can offer to custom color the hair, make wigs and clip ins etc.
To go about it, the best thing to do would be to find a good supplier buy a bulk and start selling. It's pretty easy to get people to try it once and if they're satisfied it's smooth sailing after that. I can help you if you're looking for a supplier.