Well... that's a difficult question to answer. Every buyer has their own unique taste for a home as well as neighborhood. St Petersburg has many wonderful neighborhoods to accommodate whatever your specific desires are for your new home and community, and also that fits your budget too.
I think the better question is, "How much of a monthly payment can you comfortably afford while achieving your current financial commitments?" In all likelihood, you will probably qualify for a higher mortgage than you will be comfortable with when broken down into a monthly payment. My advice would be to find a mortgage professional to get preapproved for a mortgage, but also determine how much you want to pay each month and then ask the mortgage lender to tell you what that monthly payment equates to in purchasing power. Realize that part of your monthly payment will have to be money to pay the property taxes and homeowners' insurance, and quite possibly private mortgage insurance (PMI) if you will be putting less than 20% down. If you'd like to discuss this in a little more detail, please feel free to contact me directly.