There are a number of ways to value stuff and it sounds like folks here are using just about every possible way. What you can sell something for on Craigslist is probably nothing like what it would cost to replace it, or what you should insure it for. Almost all homeowners insurance has a very low limit for what they'll pay for musical instruments and equipment. Most offer a rider or separate policy for large values of instruments, cameras, guns, jewelry, and such. Items have to be listed with serial numbers. Photos are suggested also. If items are not new enough to use new sales prices, I tend to use what it would cost to replace on Reverb to estimate values. Anyway, I have about $25-30k of listed guitars, amps, etc.