Khane's advice might be a bit hard to take, but it is good. You don't want to be in over your head on a mortgage.300k seems WAY out of your price range unless your wife also makes good money and/or you want to be house poor....
My wife and I bought our second house in May. It was $345K. We put 5% down at 3.5% (3.65%) for 30 years, and the monthly with escrow is around $2,025. We can handle the payment, and it will be better two years from now when we kiss PMI goodbye, but it is a huge jump from our first house which was $225K with 20% down at 4.75% for 30 years with an escrow around $1,200.
And yeah, taxes vary from place to place, and escrow numbers rise and fall with them. Be glad if you're not in NJ or southeast PA.