US-centric: Got a product you want to find for a steal, but not enough time to run through Fatwallet, Slickdeals, BensBargains, or any other of the deep-discount sites? Deal aggregator Combyo gives you results on any product, filtered by date, source, or category, and lets you set email price alerts for anything that's just not cheap enough yet. It's fairly similar in purpose to previously-mentioned Dealighted, but the interface is a lot cleaner and easier to run through (Original Dealighted post).
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