Is there proper bargaining etiquette ?

Going to the markets are one of my favorite things to do. I love anything to do with jewelry, clothes and household items, especially that of which is from a different culture. I wanted to make sure that I brought home lots of goodies with me, and for my friends and family! However, I was broke so I had to bargain wisely.

 In the main plazas in Cusco, you can't get anything cheap.. you have to go outside of the box a little, at least to the market San Pedro. They will try to start off high, seeing as your a tourist, but you can usually talk them down. The best trick is to just start to walk away, and they will almost always give you the price you wanted. I saw a a poncho for like 70 s./ but I ended up walking away with one for like 45 s./ Which is probably still more than locals would pay for it. However, I always felt so bad doing this! I know that these people are working so hard for their money, and I really wanted to be able to help them and give them more money- but I really just didn't have it. Then on the other hand, I knew that there are tons of tourists everyday, so they are bound to get their merchandise sold!

 Regardless, the markets here in Peru are absolutely amazing- filled with bright colors, soft textures, delicate little handmade jewelry and dolls and so much more! I ended up buying so much that I had to mail a big box home.  What do you guys think, what is the proper bargaining etiquette? 

xx SLW