Second on that - there are plenty examples of fine, plain Virginia rifles that were produced by the same gunsmiths who also could make heavily carved, engraved or inlaid pieces.
While I realize they are not believed to be Virginia rifles, the Jacob Young rifles are a good example of how one gunmaker could produce plain or highly decorated guns to suit the cusotmer's needs and means. Do a search for the thread with the photos of the Jacob Young rifles that were displayed at the CLA show a few months back (although those appear to have been made west of the mountains rather than in Virginia). You can see examples of exquisite inlay work, engraving and some carving on some of those guns, yet he also produced a very plain iron mounted gun with no carving or engraving, but with great lines and neat hardware.
There are some basic features that differ greatly from the standpoint of time and location where the guns were made. Start with a general timeframe and style you like (for example, Rev. War era, "Golden Age, late flint "mountain" style" etc.) and then hone in on a region/maker whose work you like. You can then select approriate parts to move forward with once you have a concept in mind of what you want your rifle to look like.
Take a look at the Mike Brooks iron mounted rifle on the Blog spot yesterday. There is a plain rifle that stands on the merit of its architecture and workmanship. Such a rifle could easily represent a piece made in Southwestern Virginia or nearby areas of the southern Appalachians in the 1810-30 timeframe.
Guy