I have owned MAC Blue Brown for a few years now and I absolutely love it. I bought some MAC pigmented samples on eBay and have been searching for a Blue Brown dupe forever!! I finally found one in L'Oreal HIP Pigment in Intrepid. Just look at that swatch! They're nearly identicle and soooo much cheaper!
I payed $10.95 for Intrepid, and a full size MAC Blue Brown goes for $19.50.