Need help! Inexpensive pre-amp

[AwkwardBass]

Hey forum, I ordered a little adapter to plug an instrument cable into my computer's mic jack. However, it wouldn't work. The computer couldn't pick up my bass in the recording program I used(I'm sure I set everything up right), so my bass teacher recommended I get a signal boosting preamp. I just need something with an input and an output jack and a gain knob. that's it. any suggestions?

PS- It has to be cheap, I'm a bit poor.

[GrowlerBox]

Any microphone preamp (e.g. Art Tube) will probably work, but you might be better off with one of the many USB or Firewire audio interfaces -- there are a million of them with a huge range in prices. They're always going second hand as people upgrade, and it will offer better sound and flexibility, recording options, etc.