boneyard?

as most of you know i have really been wanting to get a new gun lately the CYMA ak74 is just a bit expensive for me (i can buy it. but that leaves me with almost no money left.) so i have been looking at the boneyards on evike and airsoft gi. instead of 130-140 bucks i could spend just 80 bucks http://www.airsoftgi.com/product_info.php?cPath=275&products_id=818 (this as an example)

i currently do have an AK so if this boneyard gun doesnt work (which i am assuming it doesnt) i can just use the parts for my current AK which i was thinking about just buying external parts for so i could have something supposedly fresh. like turning it from a tactical ak47 to a run of the mill ak74. but if i bought all the external parts separate it would all come out to about 80 bucks if not more. so should i just buy the external parts for my current ak? or should i risk the boneyard deal and then if the gun doesnt work (assuming it doesnt) just use its parts?

For the example you wouldn't be able to use the handguards, it's broken near the edge. I wouldn't buy anything from the boneyard if I could buy the parts I needed brand new for the same price.

most of the time the problems are all internal. i would 90% out of 100% of the time the problem is internal. im just asking the pro's if it is a good idea. because i remember a while bag. M14 said he got his thompson from a boneyard deal and it worked fine. i am assuming it wont work. nut i realize there is a possibiliy it is fine (a very small possibility)