'Caveat emptor' is a Latin phrase that means 'Let the buyer beware.' In practice, it's therefore a slightly more wordy replacement for any of the following:
- "Buyer beware."
- "You get what you pay for."
- "Don't expect something for nothing."
- "If it sounds too good to be true, it probably is."
In general, the phrase is a good assessment of the situation when browsing auction listings that are listed on an AS-IS basis, that carry a large number of disclaimers, or that raise other kinds of red flags.
In many cases, however, the phrase doesn't really apply to eBay, especially given the sophistication of its feedback system and in cases in which buyers are careful to evaluate feedback and item listings carefully before buying.