Believe me that 200 wpc is way more than your surrounds will ever use. Much of the material going to the surrounds is only minor compared to the mains and doesn't draw nearly as much power unless you are in 5 channel stereo and then the volume tends to get the best of most of us. Your AVR is more than capable of driving the surrounds to high volumes. Remember that doubling the power to your speakers onLY increases the SPL by 3 db. the difference between 64 watts and 256 watts is 6 db. I will bet that your AVR puts out at least 64 watts especially if only driving 3 channels. Depending on your speakers the 6 db could be in the efficiency of your equipment.

Yes AVRs are generally cheaper than separates by about 50%. They also have more bells and whistles at least when they first come to market. Buying one is almost like getting a free amp section and since you have the anaolog outs you can use the AVR amp to death and then get some bigger amp.