Sorry, I'm a little confused how you run 6 speakers without buying 3 pairs of speakers, but I'll try to address the rest...
Unless you have direct line of sight of the audio components, you'll probably need to purchase 2 IR relays/repeaters so that you can control your gear from any of the three listening areas. I'm not sure how much those would cost. Or an RF-capable universal remote which (hopefully) would include a converter that you place near the gear.
Then you'll need a 7.1 receiver ($200 min) which will run on "7-channel Stereo" mode. Using the front, surround, and back surround channels should provide you 3 sets of 2-channel audio; the center channel usually mixes both L and R together, which is why a 6.1 receiver won't work for this application. Since you want all the speakers playing the same source, you don't need a multi-zone receiver.
Then you'll need speaker wire, possibly a couple hundred feet depending on where the speakers are going. Luckily, this is the cheapest part of your project. Go to http://www.monoprice.com for top-notch stuff at dirt cheap prices. The site looks shady, but they are highly reputable. Because of the long distances, you'll need 12-gauge (thick) speaker wire. 200 feet will cost about $55.
Then, you'll need speakers. Do you have speakers already? Need suggestions? Are you looking for boxes that make noise, or are you looking for knock-your-socks-off sound? If the latter, expect to add at least $100 per speaker for the indoor, more for outdoor. But this may be more speaker than you're looking for...
Hope this helps a bit.
I want to purchase an amp mainly for the stereo option of playing music
I want to run 6 speakers - 4 Indoor and 2 Outdoor on the 1 amp.
I dont want to spend too much on a multizone amp and I dont want to buy 3 pairs of speakers.
Is it better for me to buy a Surround AMP such as 5.1, 6.1 or 7.1 amp and then break up a surround speaker set. If I do this can I wire the 4 Indoor Speakers on Output A of the Amp and the remaining 2 Outdoor Speakers on Output B of the AMP to play the same music in stereo mode ?
Or is it better for me to get a purely stereo amp ?