Your crankset needs to be super strong and durable, and you should usually get a chainring from the same brand to ensure maximum compatibility, and make sure you have a great bottom bracket too. On eBay you can often get decent cranks like the SRAM Omnium with the bottom bracket included, but as far as good cranksets go, you can't go wrong with Campognolo. Built for the track, these luxury cranks will have you turning the city to your own personal velodrome. Too rich for your blood? The Soma Hellyer cranks will get the job done at almost half the price.

Campognolo Record Pista Crankset
Buy It Now at Total Cycling, $275 

Soma Hellyer Crankset
Buy It Now at Cambria Bike, $150