Amazon.com Inc has agreed to buy LiveBid.com, a 3-year-old Seattle company that broadcasts live auctions over the internet, for an undisclosed sum. Using LiveBid’s real-time software, online bidders can compete with auction attendees. The company has helped to sell OJ Simpson’s estate, the only complete Titanic ticket known to exist and a 460-acre Victorian village in Connecticut. LiveBid should help to bolster Amazon’s nascent auction business, launched on March 30 to compete with eBay Inc. With an estimated 85% of the online auction market, eBay is one of only a handful of online retailers that can give Amazon a run for its money. Like many a Seattle giant before it, Amazon wants its rival caught and killed.