Best:
Hmmm. Most of the games I own now were bought off of impluse buying. Probably my Wii system. I went looking everywhere for it. My friend and I spent a whole day trying to find it. We finally gave up and went to see a movie, we got there about 1hr too early..so we went to wal-mart..and I immediately ran to the electronics *sigh*. And I saw it...almost glowing in it's own awesomeness (woo making-up words!)...so I bought it. I was broke for the next two weeks.
Worst:
Very recently actually...I just received my VERY WELL AWAITED Croc game for PS1 today...I get it and it's only the disc..not only that but it's not the original disc...it's the greatest hits. I only paid about 10bucks for it in total...but still. I got my hopes up, and now I have to buy another one for about 20bucks.