That is a *BIG* sum of money for kindergarten. If he's happy and learning at home, I would stick with it and cross your bridges as you get to them. You're going to run into problems in the future no matter what you choose! Maybe get him into some open ended enrichment. Music lessons before kindergarten worked VERY well for us, but there are other options too. Another thing my kids learned through music lessons is classroom skills - working with a teacher, learning things incrementally, etc. Skills that might come in handy for a grade skip.
We looked at some high end private schools locally at that price point and up. I kind of felt, for that kind of money it should be an almost flawless solution. Your child isn't likely to learn anything there anyway unless it geared for PG students. All that being said, we are now homeschooling, which is working very well for us. But certainly isn't for everyone.
Good luck!
