Good find, ClaytonG. Presumably no one needs all those parts, but the Gun Busters recovered parts kit is a good way to get parts that are otherwise unavailable... The quality of the parts may vary... some may be damaged... but on average they should be pretty much okay.
The parts that are most likely to wear out or break on a pistol include springs in general, and then a couple of assemblies that work with springs: the extractor, the recoil spring assembly, and the striker assembly.
Parts like a slide or a barrel should last forever, but I can see replacing a slide that has taken a beating, or getting a second slide cerakoted in a different color or something. Not essential, but hobbies are supposed to be fun. (I buy and shoot guns because I cannot afford to buy cars and trucks and race them).
And the interesting thing is the gun parts from Gun Busters are what's left of a pistol that was used in a crime (or recovered from a crime scene, or found and not claimed, etc.). I've read that SD's are one of the most popular/preferred guns for criminals... along with Glocks. (A quick glance at some articles on the topic shows criminals get caught with a lot of revolvers, too -- presumably usually stolen -- and a host of small, cheap pocket pistols -- for obvious reasons).
For some guns that are special, or rare, or expensive, this sort of thing may give somebody else's gun a lease on life. For SD's, SD9/40VEs, etc., it gives owners an option to get parts that may be needed.