Over the years I've bought things that I wish I hadn't. Like everyone I am not perfect and I make mistakes. Many of those mistakes are pretty easily avoidable.
Purchases I regret
Maintenance for my car at a car dealer. One time several years ago took my previous car to the dealer to get the regular maintenance checkup done. It was probably something like a 50,000 or 75,000 checkup. I don't know for sure what they did. I didn't check the price before hand and I didn't shop around. Cost $400.
Earlier this year we got a dog house with a heater mat for our newly adopted dog. Its a perfectly good dog house and we paid a reasonable price for it. I don't think the dog has used it at all. Cost $180
Manual lawn trimmer thing that barely works. I since realized that our weed wacker pivots to act as an edger and I now don't use the manual tool. Cost $25. (?)
About 3 years ago I bought a remote control that will work from anywhere in the house. At the time I was going to use it to control my Tivo box while I was using the computer in the other room. I barely used it. Cost $120.
Over 10 years ago I got a X10 home remote control system. I bought this one because I followed a banner ad on a webpage. It looked like a neato gadget. It actually was a very neato gadget but I barely ever used it and it sat in a closet for years. Cost $50.
Many years ago I got an off brand CD changer for my car. It was a very good price at the time. Unfortunately the good price was not a bargain for what turned out to be a very very poor product. I really regret that purchase. Cost $130 (?)
Over the years I've bought various video games at the store because the box looked good. I have had several PC games that I distinctly remember paying $20 or more for and then playing just a few hours. These games weren't really that bad but they just weren't my kind of game or not a great use of my money. I've probably had at least 5 games in this category. Cost $100
Around 7 years ago I went on a vacation to Florida. I got a rental car from Thrifty in Orlando (who has 1.5 out of 5 stars at Yelp) and at the checkout they did a hard sell on extra insurance. I wasn't sure what insurance I needed or what kind of coverage I had so I went ahead and got the optional insurance. Cost $50-$100
All together thats about $1000 that I have spent or over-spent and now regret. This list does span many years but it is just the items off the top of my head and I probably have other regretted expenses. I've probably spent $100-$200 or more in a typical year on items I later turn around and regret. So what can I do to stop this? I should look at why I'm making these purchases and what I can do to stop them.
Mistakes I made
Don't buy things on a whim based on marketing. The X10 system and video games are things I've bought on an impulse due to good marketing which turned out to be things I didn't really want or like all that much.
Buying without research. The CD changer I bought was a bargain and I had not heard of the brand. I should have done some market research to see if they were any good. I should have figured out what I needed for rental car insurance before going on vacation.
Shop around before buying. I really should have called a few auto shops before I got my car serviced. I'm sure I could have saved a substantial amount by doing so compared to what I ended up paying the dealer.
Don't gamble on new technology formats. If I had held off a few more months before buying the HD-DVD player then the format war would have ended and I could have then safely used my money and bought a Blu-ray player.
You're still going to make simple mistakes in purchases. The dog house, remote control and lawn edger are products that I really thought I'd use but just ended up not using.