I was about to jump up and down in disbelief that no one had mentioned Blowpop yet. Thanks Tranquility
The skin that's in my avatar pic right there <---- I paid 200L for at Blowpop. She drastically discounts her old skins without retiring them, I love her for that. She has some that are even under 100L, so if you want to start somewhere, there ya go
They're hybrids with a wonderfully soft look, and I definitely suggest looking at her Mellie skins and her Tuesday (or was it Thursday?) skins.
Tuli also passes out free skins in her update group
They tend to be really nice plain everyday looks too, and have a wonderfully soft face.
And of course, Munch at Nomine (HEAR THAT IO!?) has some very discounted skins as well, in her sale section she has skins going for 200L but unlike BP she DOES retire them, so I'm not sure what she has out right now.