Cars
Holli My car. Had I waited until gas prices sky-rocketed, I could have gotten a much better deal!
Mazeway a used Saab convertible. So pretty. So unlikely to run.
Lin An S80 Volvo. It was the first front-wheel drive, twin-turbo that Volvo made (maybe in ’99) and that car was too fast for its own good. Every time I took off from a stoplight or stop sign the wheels would screech. I never could get the hang of driving it and always felt like I needed a car next to me, motor gunning, so I could look over there and say, “Yeah, I could take you.”
cmhl When I first was out of school and living the life, I decided that I needed to buy a brand new sports car. The kicker is, I had a perfectly good, free, Toyota Camry that my parents gave me, which I traded in. Stupid, stupid, stupid. But I loved that car--- and I was styling, if only for a few years, so maybe it wasn't such a bad deal after all!
Jelly - My new car. I miss my old Ford. I really do.
Kathryn, The Daring OneMy first car is WAY too small. I say "is" because shortly after purchasing it, I got married, we finished college, bought a house, had kids and have not had the money to buy new vehichles. If I'd thought ahead just a bit, I would have known that you can't comfortably fit 2 carseats, and two parents in a Prizm. Duh. Seriously, if I had it to do over again, I would be the only single college student in history, driving around in a Honda Odyssey.

Furniture
Jill Miller Zimon My youngest son's bunk beds. We NEVER use them.
Justice the leopard print chair that we have in our attic

Houses
Allison A house. In a "transitional" neighborhood outside Atlanta. Still owe 13K on the bridge loan we had to take out to get rid of it.
Summer The drafty ol' 150-year-old money-pit of a house we call 'home.' The money we spend out utilities could feed an entire Romanian village so well they'd be plunged into an abysmal epidemic of obesity and beg us to abate our contributions
Eulallia Our last house. We bought it during my first pregnancy, and then realized after our daughter was born that having no yard whatsoever was not a good thing. We lived in it for such a short time, that we barely broke even when we sold. So sad.

Thick Lashes
hadashi stock in Enron. ha ha! just kidding. a stupid tube of mascara with a brand name at a department store counter. ladies, Maybelline works JUST FINE. take my word for it.

Husbands
EverydaySuperGoddess Does my ex husband count?
ishouldbeworking Marriage license - that piece of paper has cost me so much in so many ways…

Horses
Lauren Hmmmm. My first horse, Pony. I wish I had looked around for a better horse that didn't throw me into fences.

Gadgets
Barbex My Psion 5 PDA. It was really expensive and did not use it for years. I use it as a calendar now but I could have gotten that for a third of the price.
Carmen The home security system in our old house - we were still paying for it when we moved into our current house. BIG waste of money, since we never even used it!
Mir Every single piece of exercise equipment I've ever had. Because hangers are cheaper and (in my house) serve exactly the same purpose.

Education
Jenijen A semester of college that I didn't finish, but did pay for.

Clothes
Mother Goose Mouse All those size 2 clothes that will never cover my wide load ever again.
Mary Probably those jeans I bought last month at Banana Republic. Compared to some popular jean brands, they weren't that expensive ($75?) and I thought I was totally cool when I wore them to playgroup. That is until I bent down to wipe a snotty nose and showed the world my mamacrack. What is it with today's jeans? Let me know when you want to get together to gripe about how lousy they fit those of us with more than a little junk in the trunk. Wow, I'm ranting. I'll shut up now
Sleepless Mama My husband's $400 suit, which he could have bought for a mere $175 if he'd only waited until after we moved back to a larger city before purchasing a suit.
VickyA $250, ugly, too-tight-for-my-fat-body, shiny, purple, taffeta, bridesmaid's dress. Brides who pick purple should be boiled in oil. You can't even sell that shit at a consignment store...the lady laughed and sent me away!
Donna I don't often have buyers' remorse. Guilt, yes. But I usually end up being happy I have the item, even after the bill comes in...Aside from a few items of clothing that ended up being a mistake, I can't think of a thing that answers that question.

I don’t think we should let them get away with these answers:
Buffi I am so ashamed I cannot even share this with you. You'll have to ply me with margaritas to get that out of me!
Dawn mass quantities of alcohol at one given time.