[kls]

I would second the give your current employer the option if you like it there and would like to stay. Training is a pain and 15k is not that much for having to deal with 3 months of lost productivity while a new employe comes up to speed and that's if you don't have to replace the role several times to find a good candidate. You now know that you are worth 45k so don't let your current employer short change you, tell them you really like it and do not want to leave but that they will have to match. I look at work a little differently than many. I love my job and I love to develop but I work for money, if I did not have to I would be certainly working on my own ideas exclusively so if I have to work and the jobs are fairly similar I go to the highest bidder. Like it or not employment is a business transaction where each party is trying to get the better end of the deal based on the information they have. You just gained information that you are more valuable than you are being compensated for, don't let them convince you of reasons that you are not. With that said, if you have any agreements with your current employer that you will stay with them for any amount of time even if it was just verbal, you need to honor that agreement. If not you are a free agent and you should think of yourself as such.