I get asked this question alot and I promised a guide a while back but I'm just now getting around to making it! Here is a list of websites where you can buy minky fabric for your projects!
www.beverlys.com - search cuddle 3
www.joann.com - search for Soft n Comfy
www.minkee.com.au - Australia
Land of Oh Etsy - http://www.etsy.com/listing/95419080/1-yard-1-mm-smooth-cuddle-minky-fabric?ref=usr_faveitems
Igloo0203 - http://myworld.ebay.com/igloo0203/&_trksid3984.m1439.l2754 - This seller has a wide color selection and the minky comes in 3mm and 5mm pile! She's located in Korea and shipping usually takes about 2 weeks, or at least that is when my orders arrive.
KYcutters - http://myworld.ebay.com/kycutters/?_trksid4340.l2559 - They sell Benartex Minkee Gelat