Low balling is something you are bound to run into. I sold a male bee not long ago for $400, before I sold him I received 5 different offers all under $250, I consider those low balls. Negotiating is fine IMO but when you offer less that 75% of what the animal is worth than its insulting. Before making an offer look through other ads and see what those animals are going for, this will give you an idea of what a fair price is. If I was selling a snake for $1300 I wouldn't consider $1200 a low ball unless the $1300 was already an amazing price and I specifically said that my price was firm on the post.