Like most things in life, all is not quite as it seems, especially when you are comparing apples and oranges like you do with these vehicles.
One responder indicated that the Rav4 was more luxurious and had all of those options, but you are going to pay for them. The base Prius is $22,795, while the base Rav4 starts at $23,630. The fully optioned Rav4 (with all those neat things - with leather, heated seats, but minus dual A/C and a Nav system - since it is NOT available) is $30,395. A fully optioned Prius (with leather but no heated seats, plus a Nav system) is $27,345.
As you can see, it is NOT all about the money. The vehicles are made for two totally different purposes. For instance, you can tow with the Rav4, and not with the Prius. Both of them have a lot of storage space since the Prius is a hatchback with seats that fold down. It actually doesn't do too badly in comparison with the Rav4 (21cf cargo) to 14.5 for the Prius, and that's before you fold the seats down.
The Prius gets considerably better mileage but is limited by how much it can carry. The Rav4 can basically carry all the weight that you can squash in there where the Prius is limited to 800 lbs. The Rav4, in the 4X4 configuration, can probably go most anywhere. The Prius is limited by 5.5 inches ground clearance.
It all comes down to what exactly you want. If you want a good commuter and family car that will get you exceptionally good mileage and stay on roads, the Prius is your car. If you want to go off-road occasionally or tow a boat or trailer, then the Rav4 is certainly the better equipped vehicle.
They are both exceptional vehicles that are highly praised for their build, reliability, and comfort. You really can't go wrong with either car, but you do need to do some research as to what compromises you are willing to make. You cannot make the sweeping statement that the Prius is more expensive so go for the Rav4, or that the Rav4 is more luxurious. These are things that you need to discover for yourself. Go drive both of them, even rent them if you can find them.
I hope that this helped, and I wish you good luck.