Check out the Collar Clinic. They buy and sell new and refurbished collars. I had a Tritronic's Sport 60 which I traded for a new Dogtra NCP 200 Gold. It's a good training collar with a lot of options for the money.
I didn't have a problem with the Tritronics collar other than it was a little too hot for the dog that I was going to use it on.

All the pros that I know use either the Dogtra or the Tritronics made products.

A friend of ours has used one model similar to the one you have posted. She's had some sucess with it but has replaced it after 5 years. She's gone to the Dogtra models as well.