When you buy a house and need a mortgage, an appraisal is done. Comps are done, the market sets the value. Although there's much whinging about eBay, it's the biggest market that we can actually see the actual sales price.
Our C&V appraisal forum should be taken with a grain of salt. Bikes put up for sale here are usually at a discount from what one could get at the big auction site, but less hassle, and there's confidence that the sale will go through with no issues.
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If someone tells you that you have enough bicycles and you don't need any more, stop talking to them. You don't need that kind of negativity in your life.