I know 3 specialists in Germany with stock - EU transfers between RFD's are no drama...
Prices would run between 3-700 Euro depending on condition and matching no's, military sights or diopter versions (good ones are around 4-500 quid) which may be the reason he wants a 38? Not a problem.
New barrels go for Euro 275 - presumably they are for M96's, but cutting down to a custom length and re-crowning is not expensive. I guess your client is looking for a budget option though, in which guess getting an M96 and cutting down would be cheaper than getting a M38 or M63 as they are more common.
Making sporters out of Gewehr 98's is quite common in Germany - plenty of stocks etc about: http://www.egun.de/market/list_item...ff&wheremode=on&order=price&asdes=desc&page=1
There is a tidy M38 with matching numbers currently bidding at Euro 291, I would expect it to go 1-200 higher.