Ultimate Blades for the Ultralight Hunter #2: You can buy #60 scalpel blades on eBay from US$23.95 per 100 (eg here) and you can change the blades on these CRKT PDKs with a locking forceps as shown (which weigh 24 grams – as the photo shows)
You change them just the same as any other scalpel blade (Carefully!) and using eg the tool above, by lifting up the handle end slightly then sliding the blade forward. Reinstalling the new one is the reverse of the process. Dispose of the spent blades safely eg in a hard container with a screw lid.
I know this is a somewhat stingy option given that the knives only cost about $7 each (and weigh 16 grams each including the sheath) when you buy the set of four, but it might be a useful tip. A friend who works in surgery gave me the forceps – as they dispose of thousands of them every year to waste. Astonishing – such a useful tool for fishing too! Well, they both are!
PS: I would imagine you could change the blades in the field with this too ie a Leatherman Squirt: http://www.theultralighthiker.com/leatherman_squirt/