Need to purchase a part for a Bryant Air Conditioner model 661cj042-a
Part needed HN51KC024
3100-150228
CONTACT RATING 240/277 VAC
COIL 24 VAC

Wholesale??

If you are in the business you can buy wholesale at your distributor.
OR call a local HVAC company
Or Ebay

A single pole contactor is a single pole contactor get one with your rating from any hvac supply house. It may run you around 20 bucks. Just know what your doing when you replace it, it can end up costing you a lot more. Its not only the part you buy from the hvac company you use when replacing a part, it's the warranty and the know how that comes with it.

Amazon.com: Carrier HN51KC024 Contactor 24 Volt Coil Single Pole: Home Improvement (http://www.amazon.com/Carrier-HN51KC024-Contactor-Volt-Single/dp/B0014ZFLG8)

Its not allways cheaper to do it yourself,if you don`t know how to do it,unless you have a contractors licence a lot of parts houses will not sell to you, and if they do because you are not experienced or trained in the business they will not warranty the part