You may be successful in winning and using CR-1s on eBay, but you should do it with full knowledge of the main risk, which is the possibility of losing your status and miles in the Mileage Plus program. There's the possibility that you'd be endangering the seller's account too. However, if they're selling upgrade instruments on eBay, they've already decided to take that risk.

If you're okay with paying for CR-1s, how do you feel about paying for 500-mile certificates? It's probably more expensive, and you'd be subject to the 72-hour window for Premier Executive upgrades, but at least you'd have the comfort of knowing you're not endangering your M+ account. There is also the option of paying for upgrades with miles. When I was flying coast to coast every week, I'd upgrade one roundtrip per month with miles. It gave me something to look forward to.

Here's one thing you ought to know about the Coupon Connection: You need to have "travel currency" to trade for CR-1s, such as hotel points, miles, or upgrade instruments on other airlines. No cash transactions are allowed.

I hope you decide to contribute to FlyerTalk! It's a great place to hang out.