<p>So during the summer of sophomore year, I had a mini business of building and selling custom PCs on craigslist. I would list this as an EC activity, but I don’t really have anyway to back up that I infact did this other than my word (and craigslist emails).</p>
<p>Odds are you’re not going to be asked to back it up (they audit <1% of applicants), but I think the Craigslist emails will be enough if you are asked.</p>
<p>bank statements showing deposits and other miscellaneous receipts would add to your proof points, in addition to the craigs list emails. They key is to show it as a business, an activity, and not a hobby where you were simply selling older PCs when you upgraded. Numbers of sales will help your case too.</p>
<p>sure, but did the money get deposited in a bank account after you received it in cash? Also, are their credit card records showing a regular stream of purchases of components used to build the PCs? Those might add some weight to your proof.</p>