You may or may not incur these costs when you buy (or during the time that follows), but many, many people do. And, once again, as a culture we rarely plan and budget for these expenses.

Property Taxes
Remodeling Projects
Homeowner’s Insurance
Regular Misc. Maintenance
Air Conditioning / Furnace
Furniture / Home Decor
Kitchen Appliances
Outdoor Tools
Electricity
Gas
Lawn Care
Water Heater
Water Softener
Sewage
Water
Trash
Landscaping
Installation Fees
Pest Control
PMI
Association Fees

Anyone else who has owned property of some sort could probably think back and add a few dozen bullet points to this list (yikes!).