Premier Seeds Direct
Cheap, no frills, but quality seeds. Sold in a sealed metallic plastic bags.with a basic paper label Pictures and growing instructions are on their ebay shop, but not on the packaging itself.
(Actually, they have started selling "picture packets", but they aren't as value for money as the regular ones).
They used to sell via ebay, but have since moved to selling through their own website.
I wish they had a proper search page. You can search for seeds, but it doesn't show the results in a new page. Instead it shows the results in a small pop-up. That means I cannot use a "smart" bookmark. Nor can I link to a page searching for a particular type of plant.