Long Yahoo/Google article in Wired
The Yahoo CEO had offered to buy Google for roughly $3 billion, but the young Internet search firm wasn't interested. Once upon a time, Google's founders had come to Yahoo for an infusion of cash; now they were turning up their noses at what Semel believed was a perfectly reasonable offer. Worse, Semel's lieutenants were telling him that, in fact, Google was probably worth at least $5 billion.
This was way back in the summer of 2002, two years before Google went public. An age before Google's stock soared above $500 a share, giving the company a market value of $147 billion -- right behind Chevron and just ahead of Intel.
Source: Wired News: How Yahoo Blew It