I'd make an alternate suggestion: try a Vox amPlug. These gizmos a great - they plug into your guitar, and then you plug the headphones into them. In the US you'll pick one up for maybe $30. It'll sound better and more enjoyable than a prac amp and it's cheap. They also have an aux in jack to jam with an mp3 player. With an amPlug you can play loud without hassling anyone, plus no-one will be able to hear your (many) mistakes as you learn (wish they had them for classicals guitars when I was learning all those years ago!). As well as that, the tones are actually much better than a cheap dodgy prac amp. They have volume, gain and tone control so there's a fair bit of variety to play with. Then as you get better and start to understand the difference in amp tones, you'll be in a better position to buy an amp down the track.