The NES Ghostbusters game isn't very good, but that didn't stop me from playing the heck out of it when I was younger. Mostly because I didn't have much better to do.
Fast forward a few years and I find mention of a technique for raising money that I had never heard of. It's all over the Internet, and boils down to:
buy the Ghost Alarm for $2000 and sell it back for $3000. Keep doing that until you have all the money you need.
But, I didn't have a copy of Ghostbusters to test, so I went out and found the only copy of the game within 10 miles of my house at great personal expense ($3.95 American).
I popped the game in and went to work.
I immediately went to the Shop:
Bought a Ghost Alarm for $2000
And sold it... for $1000
Then I kept doing that until I couldn't buy anything else, and the game was unwinnable because I didn't have any equipment.
But, given the prevalence and specificity of this tip, I'm thinking that there might be some revisions floating around out there that have this bug, but it certainly wasn't in any that I had.