There is a Peerhub marketplace where items can be exchanged. Otherwise, you can send an email, direct message, or simply place an order here in comments! Transactions are easy, fast, and free because the STEEM blockchain is the best blockchain there is :)
As far as other people selling products, we hear there are some others doing it, not really sure where if not on Peerhub...but as far as we know, no one else pledges to pay forward their resources to help others.
Good to know. I'll know to come back and simply comment when I'm ready to make an order. I'm still getting to know crypto but it should be super simple with the public keys!