Just months after rebuffing Google’s (NASDAQ:GOOG) $6 billion takeover bid, online deals site Groupon has reportedly been discussing a possible initial public offering with investment bankers through an informal “bake-off.”

According to The Wall Street Journal, Chicago-based Groupon has been planning to go public later in 2011 and an IPO is likely “sooner rather than later,” perhaps this fall. By offering shares to the public, Groupon could raise as much as $1 billion, the paper reported.

Last year Groupon rejected buyout offers from Google and Yahoo! (NASDAQ:YHOO) and decided instead to attempt to raise $950 million in funding.

It’s not clear when Groupon will choose advisers for an IPO, the Journal reported. Wall Street investment banks like Goldman Sachs (NYSE:GS) and Morgan Stanley (NYSE:MS) are likely to be jockeying for position to take Groupon public.

The site has 50 million subscribers in hundreds of markets and its investors include Accel Partners, Battery Ventures and Russia’s Digital Sky Technologies.

According to the Journal, Groupon wants to get a sense of valuations in a possible IPO, but is wary of overly bullish forecasts amid increasing competition.