That may work. Both repo and orig are probably uncommon, so I can see why they are expensive. I have an old shotgun that needs a new stock, so I'm making one for it. Everything on this gun is hard to find (even the 2 9/16" 16 ga ammo) . It's not worth much in working condition, so I may just use it as a wall hanger. But thats getting off topic.
The rifle stock idea could work pretty good if you fins one for a good price.