If you think you have a prevailing reason for purchasing an extended warranty, note that you need to buy it when you purchase the item. So come prepared and
Read the Warranty carefully.
First, when does the warranty go into effect? Some extended warranties go into effect as soon as you make the purchase...even concurrently with the manufacturer's warranty. So even though you are buying a four year plan you are only getting three actual years of extended warranty. The extended warranty may cover more than the standard warranty that comes with the item. Think power surges, lightening, and inhome repair (you don't want to find yourself lugging that large rear projection screen TV to your local or not so local repairman...nor is shipping going to be pragmatic) as well as a replacement set while yours is in the shop.
Bargain with the insurer
No harm in letting the retailer know you are unhappy with a high priced extended warranty. A first offer refusal may prompt a lower priced offer. Many people are uncomfortable asking for a lower price but if you are not, give it a try.
Keep the cost to twenty per cent
Don't pay more than twenty per cent of the TV or items cost. Again, remind yourself that you don't want to line the pockets of the retailer.