You might need to sit down and write a list of the sales price, the fees and what exactly was paid into your account.

Then what you think is missing.

You can contact ebay chat and maybe work through it as you say you ultimately received only $15 profit per pair.

If the shoes sold for $640 & you were supposed to receive (after fees) $275 per pair from ebay, then that is a lot more than $15 per pair. Even if you only received payment for one pair, that's still a lot more than $15 per pair. So I'm not getting the maths but maybe I have missed something.

The purchase of a printer can't be brought into the equation. It will probably prove useful to you in the future anyway.

About some of the other things going on in your life. I don't know if this still applies but I know in the past, if you were in hardship, you could actually get one utility bill waived.  It won't happen every year, I think it is a one off, but worth checking if it can be applied at the moment.

I am not sure where you live but I know that in Melbourne (and I assume most other state cities) there are several places set up for those in need to receive food, clothes etc.

If you live in SE Melbourne, message me and I'll privately send you the address of a couple of places as I have a friend who volunteers. They have a lot of people who turn up weekly to select some of the food available.

It could help you get over a difficult patch.