There are too many qualifying factors to answer this simply. If 'affordable' simply means the cheapest, that just takes shopping around for the lowest price. If you have a minimum standard on quality, desired use, caliber, etc. then you will likely eliminate the cheapest.
If you take into consideration future value, you might not even consider a new production revolver. Personally, I'd rather buy an older gun far more often than a brand new one, unless it is a new caliber or design that was not available in the past.
Do you have a purpose in mind for this revolver or is it just another addition to your personal arsenal? I have a couple or three that would fit into both of those categories for myself and I'm not sure which one will get priority if more than one becomes available at the same time.