Optional: Using a Family or Friend’s Address
If accessible.. there are so many positives to going this route…
As previously mentioned, the best option is to use an address that is REAL and that you can access. While P.O. Boxes can be expensive and other options may not be available.. family and friends MIGHT be an option for you.

Your best bet is to find some long lost relative or friend, or cousins brothers husbands sister twice removed who’s address you can use, and who has never ever signed up to eBay or PayPal! If you have a friend or relative whose name you can use, ask to use their address as well.
Note: The Key is Permission! It’s 100% legal if you have the permission of the 3rd party to use their personal details as such. You must have their permission otherwise it’s not kosher and not recommended. If this isn’t an option for you then it’s not a big deal as there are other options available.
Please Note: This method is only assumed an option if said family or friend does not already have an account with eBay or PayPal. Otherwise if you go this route and something happens to ONE of the accounts (suspension), then any other linked accounts will go down as well.
It’s the cheapest and best way to go. If you don’t have any of those people or you don’t want to go this route, then keep reading.