VWX robot kit

I just got one from RadioShack, they were 'on sale' as they put it, where the price was reduced from 300 to 150 USD.
I've eyed that kit ever since last year, but I thought 300 bucks is way too much for such a kit. I mean, while that kit includes a lot of stuff, it's just the basic thing, and if you want to make a real robot that is autonomous, you'll need a lot more money. For example, the 'programming kit', which is really just a wire and a CD, cost 100 USD.
Now it is on sale for 50, but you can't get it from anywhere, because it's been sold out. You can grab one off eBay, for about 75 USD (shipping included).
I was trying to find a DIY solution to that kit, but unfortunately it's not only a cable, but has an IC in it, which I have no idea what it does. And from doing some online reading, it seems that the kit won't let you use any advanced programming techniques. If you want to write your own C programs, you'd have to purchase a compiler, which is not free at all..

I didn't do anything with it yet, I plan to toy with it a little this week. What I would like to do is use some solar panels that I have, and make a solar bot that moves very slowly, but ideally it should be able to climb hills and move through grass. I might have to buy the tracks kit, which, on sale is about 25 bucks or so.
Anyway, once I do something cool, I'll post some pictures and details.