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 - www.etsy.com/listing/95419080/…
Igloo0203 - myworld.ebay.com/igloo0203/&_t… - 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 - myworld.ebay.com/kycutters/?_t… - They sell Benartex Minkee Gelato. It's a tie dyed minky that I used for filly Luna's mane. Some nice colors are available.
Chenille Magic - myworld.ebay.com/chenillemagic…
Sy Fabrics - www.syfabrics.com/Browse.aspx/…
Hopefully that list will make your search for minky much easier.