Bikewer

For your 50 bucks, you'll likely do well with one of the inexpensive stick-on transducer pickups. There are a couple of models available.
The soundhole pickups are generally electromagnetic, like electric guitar PUs, and as such won't sense the vibration of the guitar body much.
The transducer (piezo) pickups will, and the inexpensive ones just stick on wherever you'd like.

Unfortunately, they're kind of delicate, what with the wire hanging off wherever you stick it.
For a better job, you could place it inside the guitar, and re-wire the thing to an end-pin jack, or have someone at a shop do that... But it'd likely double your money.