I find this a good work in progress, though it would be neat if there was a way to convert your inventory list into a file for saving/printing.
Now, in terms of "condition", I find a vague "C1" to "C10" description to be a bit vague, as what "C5" may mean to 1 person is a "C6" to another and "C7" to one more. However, for those who don't know what it means, check out this link:
http://actionfigures.about.com/od/bu...gure_value.htm
I'll modify it some with some extra grades based on this scale:
•C10: Mint Condition: The figure has no discoloration, paint loss, dirt or grime, has tight joints and includes all of its original accessories. If the figure is still packaged, the package itself must be in equally pristine condition without tears, creases or damage from torn-off price tags.
•C9: Near Mint Condition: The figure must be as close to original condition as possible with the allowance of any very minor issues, such a single somewhat, but only slightly loose joint or one missing accessory. Absolutely no dirt, discoloration or paint loss allowed in this grade.
•C8: Excellent Condition: A nice, very carefully used item. A single loose joint and/or one or two missing accessories. Very slgiht discoloration or paint loss is allowed in this grade, but must not be visible to the naked eye.
•C7: Very Fine Condition: The figure must be complete (no missing limbs or broken parts) but may lack some of its original accessories, have some minor wear, discoloration or paint loss, but not noticeable among first glance to the naked eye and in the secondary areas, such as on the sides and edges. However, discoloration is minor and paint loss is only found.
•C6: Fine Condition: The figure must still be complete, but may lack most of its original accessories, have some minor wear, discoloration or paint loss, plus may have two loose joints and can be slightly difficult to stand the figure up. You may often find this grade described as "played with condition".
•C5: Very Good Condition: The figure probably has none of its original accessories or damaged accessories, and shows moderate wear, including discoloration, some loose joints and paint loss. Most collectors would still consider this figure to be easily repairable.
•C4: Good Condition: The figure has none of its original accessories and clearly shows considerable wear, including noticeable discoloration, loose joints and paint loss. Figures are difficult to stand up straight in this grade. Most collectors would still consider this the lowest grade to be repairable.
•C3: Fair Condition: The figure is heavily worn, but still playable, with very loose joints, major paint loss and high discoloration. A figure in this condition may also show some minor breaks/cracks, such as the thumbs being broken off. Standing up the figures straight is almost impossible in the grade and lower. Most collectors tend to leave figures in this condition alone. If this item is common, pass it up; but if rare, get it cheap and look to upgrade.
•C2: Poor Condition: The figure is in bad shape, with very loose, brittle joints, major paint loss and extreme discoloration to the point that it makes you want to cry. Some joints may be taped/glued improperly. What separates this from the lowest grade is that all pieces of the main figure are visibile. Unless exceptionally rare, these are generally considered bargain bin junk.
•C1: Very Poor Condition: The figure is an absolute mess, with limbs broken off, major paint loss, bite marks from dogs, burn marks from firecrackers, you name it. A figure in this condition is generally considered trash.
From what I find, your average loose figures from the early years (1988-1992) on eBay tend to be around a C5, with lots of C4's and C6's common. Those from 1993 onwards tend to average around a C6.
I hope this grading system helps, and perhaps I'll post some media describing the different grades.