I also use Bare Minerals. I have used it for about two years and it has really cleared up my skin. I love the way it looks and feels. The best part is that I can sleep in it if I don't get to wash my face before bed and it is perfectly fine on my skin.
You may check to see if you have the store Ulta in your area. Ulta is awesome because they sell everything from Covergirl, Maybeline, etc. to the higher end lines like Bare Escentuals, Smashbox, Too Faced, etc. They also have the other mineral lines like Pur Minerals and their own line as well.
From time to time they have someone from Bare Minerals come in to their store to help customers with their makeup. I went on Friday and the woman was wonderful. She helped me update my colors and gave me some great tips and tricks. I actually asked her the difference between their product and the cheaper brands. She was saying that you use much less Bare Minerals (one jar of foundation should last 6+ months) than the cheaper brands, so in the end the price is the same. There is no way for me to know if this is true. Of course, she also said the quality of the makeup is much better with Bare Minerals.