Home warranties can be purchased for a relatively low cost ($500 or so, with sight unseen, repair and replace options), but will give you the peace of mind.
Before buying a home warranty, you need to fully understand what the warranty covers and what it doesn't.
If the appliances, HVAC, water heater etc. are between 6-10 years old then it probably
makes good sense to place a home warranty on the house.
If these items are five years old or less then it may not make a lot of sense.
New homes will usually have their own warranties issued from the builder, so you won't need this for new construction.
By example, should you have a leak and need a plumber, with a home warranty, you are only on the hook for the service call fee.
Without the warranty, the plumber will charge you his service call fee plus his normal hourly rate. One repair alone can more than justify the cost of a warranty. As with anything, buyer beware.
I have seen issues with HVAC units that are only a few years old as well as appliance issues and plenty of hot water heater issues.
Most companies often several "levels" of coverage, with more coverage and/or a lower service call fee for a higher price. This fee that must be paid at time of service and your warranty should spell that out.
Choose the one you feel most comfortable with, and read the coverage information before you buy.
Read over what the Home Warranty covers before you purchase one and take into consideration what the age of your systems are within the house.
Read the coverage and, even more importantly, the exceptions before you choose a warranty company.
The warranty covers a good deal of stuff, but not everything.
Do not buy a warranty simple for its cost alone.
Many buyers will have it written in to the contract that the seller will pay for the cost of the home warranty. It's just another item that should be discussed when putting together your offer to purchase.
What I like best about these is after the first term of the warranty expires many of them can be renewed, which works out great for an aging home.