Beauty Boxes.....worth it or not?

Well I've been noticing in my searching that there are a lot of different beauty box subscriptions you can take part in. Most of them seem to cost $30 and under, but are they really worth it? Do you get something that you actually use? I've notice on most blogs about the beauty boxes people have paid for they only get maybe one item they like...Sounds like a total rip off to me, why do you just go to the store and make your own beauty box every month with full size products? That's my plan! Please stay tuned for my own personal "beauty box of the month" creation.
However this doesn't apply to things like the Vox Box or something like that because those are product testing boxes you get from a site or company for free.