the hatchbox on amazon has good reviews - one of the best reasons to buy at amazon - as well as prime.

Never heard anything bad about hatchbox.

lol globalsfsd sell samples.
So yeah they do have 'plain jane' pla. Sort of ;-)
They've got polymaker's polyplus and poly max. Also colorfabb's pla/pha

But generally it would be for samples of the more exotic and expensive filaments.
You'd be surprised what you can make with just 10 metres :-)