What tool did you make the biggest mistake buying???

[winchmaster]

This question came up in my mind when answering the drill press thread. For me it wasn't a costly mistake but one that if I had thought it out better would of definitely taken a bigger step.
IT would be my band saw without a doubt.
I figured wrong, that since I was working with small pieces of wood and making small cuts I would not need nothing more than a hobby band saw. Yes It works but I find myself overwhelming it way too many times. Plus if I had thought about it a full size band saw could of been used to mill rough stock. Instead I waste way too much material using the table saw's fatter blade.
It's also the only tool that "has got a piece of me" because I pushed it too far.
Anyone else wish they had upgraded right away or are thinking about a tool that they think would fill your shops need?