We introduce AuctionExplorer, a suite of tools for exploring databases of online auctions. The suite combines tools for collecting, processing, and interactively exploring auction attributes (e.g., seller rating), and the bid history (price evolution represented as a time series). Part of AuctionExplorer's power comes from its coupling of the two information structures, thereby allowing exploration of relationships between them. Exploration can be directed by hypothesis testing or exploratory data analysis. We propose a process for visual data analysis and illustrate AuctionExplorer's operations with a dataset of eBay auctions. Insights may improve seller, bidder, auction house, and other vendors' understanding of the market, thereby assisting their decision making process.