I'm not sure how much you know about proxies, but many common proxies are risky in regards to creating eBay accounts.
I don't have any service recommendations, but I don't recommend using some random free proxy online.
Most phones have dynamic IP addresses, which means they change when they are reset.
You could check if your phone has a dynamic IP, and if it does, then you could access your account from your phone's internet.
In most cases, if you wanted, you could even tether this connection to your computer.
Of course, you would have to be very careful not to get your phone IP and home IP crossed when eBay (or the eBay app running in the background) is open.