The good news is that you can get just about any collar on the market for $500. Really most of them out there are pretty good with exception of what you can buy at pet superstores.
The features that you need depend on the type of dog that you have and the type of training that you will be doing. I also recommend certain models based on whether you are training the dog yourself versus having the dog trained and then working on a certain level most of the time.
For example, most of my clients are happy with a collar like most dogtra models or the Einstein by e collar technologies however I don't recommend those collars if you are training yourself because they all have a rheostat and an LCD display that forces you to have to take your eyes off the dog in order to adjust up or down. In that instance I would recommend a tube style tranitter with low,medium, and high at your fingertips without taking your eyes off the dog. The two I would recommend are the Garmin pro 550 or the new dogtra edge rt. I would not recommend the trash breaker, pro 70, or dogtra edge because although they have a tube transmitter they have limited levels and therefore have large jumps between them. They are more for dogs that are already trained. I would also stay away from the garmin delta because as it was said there are a lot of contact issues with the fixed short probes.www.gundogsuply.com
has a good collar comparison with videos of the features of all and I believe you can get most at Cabelas.