Matt,
It's good that you want to try the hobby, but also know that you only want to spend X amount in case you don't like it.
Here's a good one to try the hobby with, that comes with a good 3 channel radio. "Sky Skooter Pro 2 - available at Tower hobbies on sale for 149.99 and comes with EVERYTHING you will need to get started. Plane takes 20 mins. to "assemble". Comes with the plane, radio, battery, charger, instructions, ect.
A lot of the other little cheepie electrics don't have a very good radio, and in fact, most of them come with a radio that is more like a car, or boat radio.
If you decide you like it, then you can always get a Hangar 9 "Alpha" ready to fly plane for 399.99 (.40 size glow powered, with all the basic stuff), You will still need to pick up a few items if you go that route, like a glow plug igniter, some fuel, ect.
Also, as far as learning to fly these, it's best if you can find someone to help, (use the "finding an instructor" part of this site) Although with the sky skooter, and other "park flyer" type electrics, your chances of self teaching are MUCH greater. They aren't THAT easy to fly until you've done it a few times, just like anything else.
Oh yeah, the sky skooter will fly in the area of a baseball field.
Always remember: If you think the plane is going to fly out of site, or you really can't tell what's going on with it, just cut the throttle.
Good luck, have FUN, and keep at it.

Jetts