The fastest, cheapest way is Jammer Live. I saw it at Guitar Center this week for $29 bucks ! (Or was it $59?)
That's an easy way to get into it, but there are also many older model's that are slow sellers that you can buy for a "song".
For example - I can sell you a brand new (old stock) Roland E36 that has 61 keys, styles, sounds and speakers for $200.
In todays world of features, it's a dog, but the basics are all there. Plenty of styles to cover most genres of music, and it's portable and self-contained. It's just a thought.
The cheap route is Jammer Live.