My retainer was 5K (but I paid less than the normal fee because I'm related to a judge). I believe my husband paid about the same price. None of it was refundable... I've noticed the lawyers tend to burn through the retainer pretty quickly.
Get some references if you can (Divorce/single groups through a church or otherwise are a good place to do this) Before settling on one lawyer, talk with, or meet with, a few of them if possible. Go with a list of questions and write everything down.
Good luck!
There is no arriving, ever. It is all a continual becoming.