We're close enough to drive to Disney, so this isn't a problem for us . . .
but I did do this when we did our western national parks driving trip. I got a large pre-paid mailer from the post office, which I think was $14. If your trip's shorter, you could probably do with a smaller /less expensive box. Given the right circumstances, I'd absolutely do this again.
The $14 box was large enough to hold full-sized shampoo, sunscreen, and everything else our family of four needed for three weeks. I did put everything into ziplock bags, but we had no problems with the liquids. They did put a "liquids" sticker on the box when I took it back to the post office.
Yes, we could've bought toiletries when we landed, but we were arriving in Las Vegas late at night, and I did want a toothbrush and toothpaste at my disposal right away. We also mailed a lighter, kitchen knife, and my husband's pocket knife. Those things wouldn't have been allowed on the plane at all. Also, I use a couple dermatologist-recommended skin products (Vanicream products) that aren't expensive, but aren't easy to find.