Well, if you do a lot of practicing just for your head, you may want to pick up a Korg Pandora. I have one of the older ones, and am eyeballing the PX4D. Nice little boxes. They do a lot of the basic effects that you'd want (Compression, a couple flavors of distortion, Overdrive, Flange, Autowah (Ottowa)) and some basic amp modeling. They generally run
'bout a hun'red.
Also, earlier Limmo gave some tips for buying a guitar. The same thing goes for an amp. Take your guitar to the store with you, since you KNOW what it sounds like. Then start plugging into the amps. For the longest time I was really intimidated by the music store dudes, and making any kind of noise in the store. F' that. Go in, twist all the knobs play through your single coils, play through your humbuckers, play with your tone all the way down, play with it all the way up, muff on, muff off. Eventually you're going to fall in love with one of those amps. It might not even be the more expensive one!
I just picked up a guitar the other day (For years I've been playing a fender accoustic, and a post-bankruptcy Kramer, both are plywood guitars. Not excellent.) and I did the same thing. Just cycled through a bunch of them. I had an open budget for purchasing. I didn't end up with the most expensive one I could buy, but this
Godin SD just felt so good to play. It came down between the Godin, and a G&L. Both were nice. But this Godin just felt RAD.
So I can't give you any geekery about watts, or knob length or that stuff. Just kinda play with em and decide which one you love.