Don't Be Intimidated. . .
Don't be intimidated by the ebay stuff. I've tinkered alot with ebay over the last several years and it has been profitable. My advice to you is to register with paypal. Don't be intimidated by the fees associated. Yes, you do have to pay. But you also need to recognize that you would never have as many potential buyers come and browse a table set up in your front yard at a yard sale - as you would have viewing your item on ebay.
One person may be willing to pay $2 for your item at a yard sale and you've sold it for free. That's great. However, 200 people may view your item on ebay - and 15 may end up in a bidding war over it. The results can be astonishing. And if your final bidder is willing to pay $40 for your item - then spending the $2 you would've made at your yard sale - on ebay and paypal fees instead - is definitely worth it.
As for the boxes, if you ship via the US Postal Service via Priority Mail and visit their website for shipping supplies, you will find that they will ship the boxes right to your doorstep - absolutely free of charge! Surf through the site - they have it set up to look like there are costs for the items. However, you will see that all the priority boxes, labels, etc. up to the 12" box are at no charge. Add them to you cart, it will total an invoice - and the total will be $0. A week or two later - they are on your doorstep.
As for paypal, I do it because you can accept credit card payments, receive payments the day your auction ends rather than waiting 7-10 days to receive a check that has to clear - or a money order that is possibly fradulent - in the mail. Then you can transfer your paypal money right into your savings or checking account. The funds are available with 2-3 business days. You can also use your paypal funds to shop on ebay and many other sites on the internet. They take their minimal fees (pocket change) right out of the funds received from your bidder upon payment receipt - so it really isn't an "out of pocket" expense that you have to turn around and pay to them. Accepting paypal attracts more bidders by offering several ways to accept payment. They can then use credit cards, e-check payments, or debit cards to pay for their auction win. You really decrease the number of potential bidders by limiting them.
And if you want to pay your ebay fees prior to the monthly billing - you can do so through your "my ebay" page anytime you like. Additionally, you can remit the payment directly from your paypal account. The money comes straight from the funds you've collected from your auction listings rather than out of your pocket. If you pay them weekly - they don't accumulate.