Karnage is absolutely 100% correct here and I say this as the very first person to setup a Nostr address service probit in December 2022.

You don't need a Nostr address. You don't need to purchase one from me or any other provider. Though, Nostr addresses are nice to help you be found and identified in a human readable format.

(I'll help you setup your own if you have a domain and website! DM me!)