eBay means you have to pack and ship at a reasonable cost. Buyers have been spoiled by Amazon free shipping. I sell on eBay and I’m asked constantly for free shipping. My response is a somewhat nicer version of “let me know who can deliver it for free and I will happily drop it off”.
and eBay means lots of fees for sellers and you will get a pesky 1099.
Selling locally depends on location. Some areas you can get full value, others you won’t get close.
on modern bikes, start with bicycle blue book, their pricing is low but that will be the guide buyers use too.
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Please don't confuse ebay "asking" prices with "selling" prices. Many sellers never get their ask price. some are far from it. Value is determined once an item actually SELLS. Its easy enough to check SOLD prices.