I would try to find a used Fender Mustang 1 at GC or on Craigslist. I'd be willing to bet you could score one for $50. I bought one new for $100 and it sounds great with headphones. You can program a bunch of models, it has an aux port so you can play along to backing tracks, and you can do direct recording. The mini amps such as the Roland, Fender, or Vox are also light, inexpensive, and have much of the same functionality of the Mustang 1.