Mike,

If you are buying them anywhere other than an authorized Titleist retailer, you bring in the possibility of purchasing a counterfeit set.  One other issue is that there won't be any warranty associated with the second hand set.  

Cameron

1-888-TITLEIST 

Concur with Cameron.

The cost of reshafting the club is approx $17 labor plus the price of the shaft and grip (assuming a Titleist grip is a bit more pricey - about $12-15).  I believe the cost of a Project X or KBS Tour Shaft is about $36 each.   So let's say about $65 per club for the shafts and whatever price you paid for the irons (the low price for a set of AP2 irons is $450 or so on eBay). $115 per club with price of the irons plus the reshaft.

The cost of a set of AP2 irons is $1000 or so.  That's $110 per club. 

Thanks for the feedback, makes sense.  It doesn't appear that the $ savings associated with building vs. buying a set of irons to my specs will be significant enough to offset not having a warranty or not knowing the history of the used the clubs.  

The time when it makes better sense to reshaft is when you are doing it to a set of clubs you already own (then the club cost is $0). 

The $17 labor is $5 to pull the head, $10 to assemble, $2 for grip install. 

I had a set of Eye 2 irons (5-PW) that I had reshafted to TT Lite XL regular from a mixed bundle.  I was able to get the install for free since the shipment was delayed.  The price of TT Lite XL is about $9/shaft.  I was charged for a regrip/cut.    The cost per club was $25 including pull head, shaft, grip install and shaft cut.

Also, in buying used clubs, you should already know what shaft works.