I can tell you my ’selling LP’s on eBay’ experience.
My original motivation was to weed my alphabetical system that got overloaded so I didn’t need to re-shuffle everything.
It’s more work than you think, I stopped for a while when I went on vacation (not here to ship), and never went back to selling.
I sold over 100 lps before I stopped. Years ago, same reason, to make room, I sold around 150 pre-recorded Reel to Reel tapes. Same thing, set up a quick consistent system. same thing, average gain, worth it?
Historic content, people from those eras have passed, retired with less income, already have a lot, and younger people are not interested, so your list of buyers is constantly reducing.
Starting Out: I decided to ’trust the market’ simplify the listing process, forget trying to ascertain rareness, let the buyers who know bid them up to appropriate levels. Also to avoid ’professional’ grading which is needed for experienced buyers.
Trusting the market works ’to a point’. I got up to $75 (Led Zeppelin, ...) and then many sell for my starting prices. You have to work carefully to keep your 100% rating. You do develop a following, and positive feedback builds.
BUT: MANY sold for my $7.99 starting price (+ $4.00 shipping). After fees, shipping materials, I cleared only $4.00 on those. You can feel like you are working for somebody else, even foolish.
The Work"
Set up listing system.
Photos: lighting/surface/tripod/camera settings/color consistency need to be worked out, after that it’s fairly quick. I'm an amateur enthusiast photographer, with very good cameras and capabilities far beyond cell phone photos, but, my wife lists clothes, using cell phone photos, their cameras have gotten very good these days.
I got it down to: Front cover with the vinyl sticking out half way; Rear; if Gatefold 2 more photos, IF inserts with info, you have to decide, a few more never hurt, you get 12 free photos each listing. If lots of small interesting text, I might take a few partial views (so it is readable on line).
After that, I had two categories: Darn Good (only slight essentially inaudible scuffs) and Very Darn Good (no scuffs). I don’t sell scratched or seriously scuffed LPs.
Transfer the photos to computer, crop, perhaps edit a few clicks, then off to list. Modify an existing listing is the fastest, it has your general notes about condition, shipping, change the title, change the photo, change the specific notes. Next: two links, one wiki leaks with ’fun’ info, other Discogs with ’version’ info.
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So, my answer: decide who is capable and willing to do the work first.
Then research, find value before you list the ones that will fetch a good price,
and, as you are asking, list where? I was too lazy, but a few places simultaneously for rare ones makes sense to me.