You might want to try locally before going to Ebay and the like.
Comic shops will buy used stuff, but you have to haul it over and they'll want to get it for cheaper than you likely could sell it for online (they have to make a profit), but no shipping and no chance of theft/fraud crap either - they look through your collection and offer you a flat cash fee (or more if you take it "in trade" but cash is obviously better) for the items they want. Anything they don't want, we take to a company called Half Price Books (which buy things, but for way cheaper than we'd get from the comic shop), and get a much smaller amount but the items are mostly sold and done with in less than an hour or two.
I've had mixed success listing items on Nextdoor. You can make sure it's registered known people in your neighborhood (can't become a member of Nextdoor without basic verification), and you can list items for whatever and meet up wherever. So like Craigslist, but a little less scummy (?) but also with specialty items like comics/manga, you won't have much of an audience for it - had great success with household items, not a nibble with unique stuff like a Star Wars lunchbox or action figures.
The husband has been culling out his action figure and comic collection for a little while now, and has been happy to get rid of it for anything. Collections are not worth the money you paid any more because stuff isn't really rare or hard to come by, and you'd be damned lucky if you break even at this point.
I can't imagine it would be worth the amount of time taking and editing photos, writing descriptions, posting each one (even if you do it in lots) and then print out, package and drop off each package will make more sense than just taking a bunch over and selling it off in bulk, but it just depends if you do have anything truly valuable/rare enough to justify the amount of time and effort to sell off a large amount of items.
Honestly, you may need to do some basic research on what your items are actually selling for - what you paid is likely MUCH more than what someone is willing to offer, so the idea that you could get over 1k or better may be grossly overestimating. But if you know what an item is selling for (not listed, SOLD prices) then you have a better idea of what you should pull out of your collection and list on Ebay and the more common stuff could be sold in bulk to the local comic shop - basically capitalize on your time and efforts so the good stuff nets you the best profit and the other stuff doesn't waste your time.
And in future, check out the local library for your manga/comics fix. Ours actually has a huge variety and it means we can read without having to buy. Or check in with friends and see if you can borrow (and take very good care of the borrowed items so they'll continue to lend).
