The best way to find out what your house is worth is to put it on the market. That is if your thinking of selling.
Either way you can have it appraised by a certified appraiser, or get some free BPO's to give you an estimate of its value.
Take the lowest BPO put it on at that amount, have an open house on Saturday and Sunday. It should get multi offers and hopefully many will be above the asking price. If it is below the asking price and you have multi offers, then that's what its worth as well.
Get a good agent to represent you.
If you need some suggestions for your area, let me know.