Blahman, I was speaking of pre-Rev pieces. I happen to have a copy of Neumann here, and I don't see any "poor-boys" there. On page 233 he has two without patchboxes. One has a buttplate and a fowler triggerguard, and while the pictures are not very good quality, the gun looks to me like well made piece in fowler-style, which would preclude a patchbox anyway. The other is an extremely plain type, but it also has a square-to-octagon barrel, and is not definitely pre-Rev. Now there are two other pieces on page 234 worth looking at. number 1 is obviously made by an amateur, but one that was intent on making the best gun he could- the thing has the whole set of possible parts, including a toe-plate. In other words, not a "cheap" gun, just an amateur job. It may be a nineteenth century replica! The other one, number 2, is actually a fairly fancy piece with a lousy patchbox, probably a later addition.
Letrs look at two more rifles for a moment. In shumway's Rifles of Colonial America, number 137 is missing the buttplate and entry thimble. However, it has a patchbox and is carved behind and around the cheekpiece. Having said al that, I now notice that Shumway dates it to 1785-1810, making it irrelevant . The second piece is here
http://www.palongrifles.com/home/PicturePages/Pics_white.htm
This is the closest I have found to a poorboy type that can be confidently dated to the revolutionary war or better. Note that it has a buttplate, nosecap (I think) and sideplate, but has only one thimble. I can't tell if it has a greasehole or just a missing lid.
By the way, straight rifling, while rare, is not due to lack of money- there is a very fancy JP Beck piece with straight-rifling, a single-set trigger, and silver mounts.
Anyhow, to conclude, I still don't see much evidence for poorbys earlier then the 1790s, if you define a poorboy as missing at least both the patchbox and the buttplate. The only one that might qualify is the square-barreled piece, which is something of an oddity. I think y'all are getting hung up on the supposed costs- simple carving is not that hard to do, compared with other tasks, and people liked decoration. Even Brown Besses were carved! There are rifles obviously built for use out there that still have carving, patchbox, etc., even those that were evidently made from re-used parts.