In agreement with that sage of weaponery, Kyrie, I would posit the appropriate analogy for a mismatched part on most collector pieces is the wine/sewage analogy:
If you put a spoon of wine in a barrel of sewage, you have a barrel of sewage.
If you put a spoon of sewage in a barrel of wine, you have a barrel of sewage.
In short, value sinks to the lowest common denominator. I must say that I likewise concur with my esteeemed colleague Albert on rarity of the individual piece playing a large part in negating this effect. The example that comes to mind immediately is Lugers which are all matching except the magazine. Most Lugers do not have matching magazines. Market prices reflect this. When one comes along that does match, add about 25-30% premium. If it should have two matching magazines, add 50-75%. As an example, I recall a 1917 Navy Luger rig some years ago that had 3 matching magazines. It sold for nearly $8,000 when other rigs with mismatching or a single matching magazine were selling for $4500.
Collectors are finicky people; we like what we like and the market will reflect it.
Tom A.
Tom A. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />