Note, that that the Treet blades are also available through Rite Aid. Also note, that the "looks" blades listed on this page are garbage that are not worth buying, and that all except for the Gem blades are Carbon blades, which will rust if not properly dried between shaves.
The Ted Pella blades are available in bulk through Ted Pella:
There are at least three recent threads on this topic in the razor blade forum. I just got some of the blades from Amazon and really like how they shave.
Don't get those ones. My favorites are the Gem Personnas from Walgreens. The only other ones I've tried are the Ted Pellas, and I don't like them nearly as much.