Consolidators are the people who put those small ads in tiny print in the back of the newspaper listing low fares to far-flung places. You can save the most on flights to Asia and Latin America. Consolidators won't save you too much if you're going to Europe in winter because fares are already so low at that time of year. But in summer, you can often find substantial discounts. Buying from a consolidator can be risky if you don't take certain precautions.
Some scam artists sell stolen tickets and tickets bought with miles purchased from frequent fliers.
Some simply take your money and run. Before using a consolidator, you may want to check out its reputation with the Better Business Bureau in the city where it is located, and also with the state attorney general's consumer protection division. Also, if your transaction is with a travel agent, your payment is protected if the consolidator goes out of business or doesn't deliver what was promised. A good travel agent will often have a relationship with a reputable consolidator. Be particularly wary of cash-only transactions and of tickets with printed prices that are higher than the amount you paid.