Since I only use coated end mills for Aluminum, I have had great luck from this ebay seller: DrillMan1. I think he gets surplus because the inventory is a little hit or miss.
I have purchased 1/32, 1/16, 1/8 and 1/4 (2 and 4 flute , flat and ball) from him. (ave cutter cost was $8 to $10 each)
I also recently bought a 6mm collet and then purchased some 2 and 4 flute cheap (TiAlN) end mills from Banggood.com and have also had great luck. I ran a set of 60 Aluminum (1/2" thk) clamps using one 2-flute cutter and it still looks brand new. (Cutter cost was about $4)