One thing that you have to be very careful with when looking at taxes and insurance is that if you buy a foreclosed property, the taxes may be based on the value of the house last year. So, if you buy a house for $100,000 but it was worth $200,000 last year, your taxes may be based on the $200,000 property for the next year. This is especially important when qualifying for a loan. If you are told that the property's taxes SHOULD be $100 based on a $100,000 property and the loan officer is told that, he/she may qualify you using the lower amount of property taxes. When it's time for your loan to go through underwriting, the underwriter will use the $200,000 value ($200 property taxes for example) to qualify you. If you don't make enough income to cover the higher property amount, your loan may be declined. After you buy the house, you may look into filing for homestead exemption so that you can obtain the lower taxes.
Similarly, if you buy a house from someone who is retired, his or her taxes may be lower than normal (many states don't charge senior citizens school taxes after a certain age). You may think your taxes are lower when in fact they are higher. This can result in the lender not collecting enough money for escrow (the money used to pay the taxes at the end of each cycle). This will in turn cause your mortgage payment to go up if you allow the lender to pay your taxes and insurance.
Home owner's insurance can vary depending on your history with houses. If you've had claims in the past with insurance companies for repairs, your insurance quote may be higher. Credit can also affect your payment.