This is one of those questions that the answer is -" It depends". But let me offer an overview. The older the home, the more potential for upgrade cost. If the house does not have updated grounded electrical that is a cost for some point in the future. Copper plumbing is another one associated with and older home. Many were made with stainless steel pipes that by now are showing their age. Other items like the furnace or air conditioning age may be a factor when looking at updating expenses. Last but not least, the roof age and the condition of the foundation.
If you are looking at a home in the mountains or beach area, there may be cost associated to retaining your property line. If erosion is a factor, there may serious cost to be considered in maintaining retaining walls and the foundation.
If you have a septic tank and not public sewer, be aware that tree roots can damage the drainage system. Equally, if you have a well, changes in the under ground water table may require re-drilling for water.
You mentioned taxes but if you are in a more rural area and sidewalks have not been installed, this may be a cost in assessments later down the road. ( no pun intended) Also, look for easement issues on the property. This should be disclosed but it is always important to read the title and deed carefully.
If you are purchasing the home as an investment and will be renting, many times new investors underestimate maintenance and repairs. Sometimes rental property situations require legal action, so adding the cost of legal representation may be something to consider.
If you are obtaining a conventional mortgage loan, look for hidden cost from the lender. Question every fee and I recommend having a back up lender to help you question any charges on the paper. If the first lender doesn't come through, you already have the back up lender who knows your situation and is ready to go. Talk to lenders before shopping to compare "typical" cost for completing the loan.
Make sure you obtain all the appropriate inspections before your contingency period is over. Check into the "general plan" for the city to find plans for new highways, or other activities that may alter your home value.