If your limit is really $40, then there are only 2 RC's I can recommend:
I just bought the radio shock Xmods 1/16 buggy.
The "special edition" kit is $40 (on sale)
It comes with a upgrade motor and upgrade 4wd kit.
Unlike most toy rc's, it has proportional steering and throttle.
It's speed is only a bit faster than most toy rc's. But with the 4wd upgrade installed (which is easy to do) it can drive over packed dirt or even some slightly bumpy terrain.
It is a bit large for driving in the house, as the turning radius is a bit large. But good for outside on the driveway....or maybe in a larger basement.
The second is the Miasto rock crawler. It is not fast at all....but rather it is 4wd with locked diffs, large grippy tires and a lot of suspension travel. It doesn't have proportional controls, but is pretty sturdy and can drive a lot of places other toy rc's simply cannot. And it can be fun indoors just by using household items to make your own crawler course.
These run a bit more online, but are $30 at walmart. Again, not fast, but with the 4 wheel drive and lots of suspension travel it can drive a lot of places. Ive wrapped mine with saran wrap to drive in the snow. Ive taken it threw short grass. dirt and such is no problem. You can find reviews of these on youtube.
of the 2, I actually like the rock crawler better. The xmod buggy does have some optional upgrades you can get later (9.6v battery and truck body) but simiply cant drive as many places as the crawler can. But either of them is the best of the toy RC's currently available today.