Quoted from Pin_Guy:This is a tough decision and ultimately one that you will need to decide on your own.
Keep in mind though that AFM is the rumored CGC next title which could have a negative effect on the current value of the Bally machine, just as MMR had on its original counterpart.
I say keep what you have and wait unless you can trade with some on local for a while ie loaner swap type deal. TAF is one that everybody wants so if you do sell it may have a harder time getting another one. I have played all 3 and would buy them if price was right but i not paying the current price even if i had the money. I personally think they are way high just because everybody wants one and someone will always pay more then the next clown.