I'll try and help you. You really have to be careful in the are of buying a trained squirrel dog. There are a lot of disreputable trainers out there. Do a google search and you should be able to come up with a website for squirrel dogs. You'll find they come in all shapes and sizes.
The problem is when someone has a really good dog they don't sell them, get it. They tend to sell dogs that don't perform well but do perform.
Your best bet is finding a pup out of a decent breeding and train it yourself . I hope this helps you.