A reader first postulated this idea to me on this site a while back. What if Google (GOOG) came out with its own online payment system to rival PayPal? Given eBay's lack of success in trying to topple the market leader years back (eBay created Billpay, only to later fold it and purchase PayPal for $1.3 billion three years ago), I was doubtful as to the merits of such a strategy and how it fit in with Google's overall focus on search applications.

However, The Wall Street Journal is reporting that Google plans to launch its own online payment system later this year. I still believe, given PayPal's overwhelming lead and seemless integration with eBay, it will be difficult for Google to make significant inroads in the business. But you still have to think about the possible ramifications.

There is one way Google could really put the heat on PayPal, in my opinion. As eBay has seen its domestic listing growth slow, they have responded by raising prices both on their auctions and for online payments. This has infuriated many sellers and caused them to look elsewhere in many cases. In fact, eBay saw month-over-month declines in total listings earlier this year, which many attribute to their fee hikes.

If Google decided to meaningfully undercut PayPal on price (PayPal currently takes 2.9% of debit and credit card payments received, plus a transaction fee), eBay would have to react with price cuts of its own, or risk losing meaningful market share. How vulnerable is eBay to such an event? Well, in the first quarter of 2005 PayPal accounted for 23% of eBay's revenue.

As a Google shareholder, I am hoping they can make a dent in eBay's business. If they can, eBay's stock, which currently fetches 38 times 2006 earnings, may be ripe for selling. For 42 times 2006 earnings investors can own GOOG shares instead, and enjoy a higher growth rate, more EPS upside surprise potential, and fewer competitive pressures.