You could call some home insurance companies and get a quote.
We haven’t owned a home in awhile, but you can ball-park insurance at $100-$300/month, depending on whether or not you’re in a fire or flood zone, if you have dogs, a pool, or other potential hazards.
Maintenance on a 15 year-old home can really vary. It depends on the degree of deferred maintenance (what the sellers should have done, but didn’t) and your preferences WRT upgrades and how well you want to maintain it. Whether or not you’ll be doing your own work, or hiring someone else to do it can affect your costs greatly. You can spend just a few hundred, or you can spend a few thousand every year. In general, many people figure it can run around .5-1% of the price of the home, annually. Remember that you will have to save up money for the BIG things — a new roof, A/C or heater repair/maint/replacement, water heater, electrical, plumbing repairs (like when the pipes under your slab leak), walls/fencing, etc.
Utilities also can vary. If you have a lot of hardscape and drought-resistant plants, and you are an uber-conservationist when it comes to water usage, it would probably run around $50 or so per month. If you have lots of grass and a large family that uses a lot of water, it can run into the $100-$250 range. Gas and electric can run from $75-$600+/month depending on whether or not you are frugal or use the A/C all night and day (A/C is probably the biggest expense WRT energy usage).
These are all estimates, and as you know, it really depends on the property and the owner.
