I'm sure that is a reproduction stock. Better pics would help.
I have seen original M1A1icon stocks that were M2 cut. That would probably have been done post WW2.
It is possible that an IBM could have been put in an M1A1 stock in a rebuild, but that one does not look to be a USGI stock.
Not good enough pics of the holster to tell if USGI. Real $200.00 and up, repro about $30.00
I think the seller is way off on the price. Gun dealers are like that. Whole package worth more like about $650.00/$700.00.....Frank