Since my son did not respond to me about 30th b/d, I sent him dancing deer combo, of brownies and cookies, and $$$. I like to order from local cupcake factories, but I had no support. I do t wish to pay as much for shipping as the product.
Costco has cake pops as well as other birthday cakes that include shipping.
http://www.costco.com/Summer-Confetti-Truffle-Cake-Pops-20-Count.product.100302570.html
http://www.costco.com/Summer-Classic-Truffle-Cake-Pop-20-Count.product.100302566.html
http://www.costco.com/Summer-Romance-Truffle-Cake-Pop-20-Count.product.100302569.html
I sent my D a decorated/wrapped box of homemade cupcakes to share with her friends, cans of icing and sprinkles, party plates and napkins, a party tiara, a stuffed animal and cash, party blowouts and poppers, bubbles, glow sticks, beads, party hats, and 18 cutout images of a cute thing she liked at the time. They had fun with all the stuff. She kept the box and had me send it to her (refreshed a little) the next few years, too.
Go someplace like Things Remembered and get something engraved that includes the date. (“Happy 18th Birthday - X/X/2016”) I had a bottle of alcohol engraved for my son’s 21st, but that doesn’t really work for 18.
The cupcakes and tickets are good ideas, but only the memories can be kept past that day.