EBAY(PayPal) reports your sales to the IRS under these standards:
Sunday, August 10, 2008
Paypal Has To Report To IRS (eBay Sellers)
The new Housing and Economic Recovery Act signed into law requires Paypal and others to report to the IRS. This law will take affect in 2011 and will be reported in 2012 for the 2011 tax year.
You are excluded from having your info reported if:
1. If you receive less than $20,000 a year in payments; and
2. If you have less than 200 payments.
You will have to make sure you keep good records. For more information visit the official Paypal Blog for more information.
Anything less than this, the IRS will not have any information on you sales. That being said, if you make money off of EBAY sales, by law, you need to claim it as income. But it gets very complicated. You have to take in consideration what you paid for the sets, any commissions paid, other costs of your business, depreciation, etc...It can get quite messy for a few LEGO sets.
I get the feeling most EBAY sellers don't pay tax on their sales and while I'm not giving financial advice, from what I've read, the IRS is not looking to audit you over a few sales on EBAY. They have bigger fish to fry. Just my 2 cents...