I've purchased from elf, so I'll share - the quality is about as good as what we used to call "dime store makeup" - not quite as good as, say, maybelline, but not bad either. The sizes are definitely not sample sizes; again, they're not quite as large as Maybelline or Cover Girl, but you do get a good amount of product. The real bargain is the brushes - I ordered two, and they're very good quality - not just good quality for a dollar, but good quality, period. I would be willing to purchase those again.
The order took a bit longer than most online vendors, say, a couple of weeks to get to me.
HTH!