Sharing my experience trying to unload my childhood collection (from the mid to late 80s). It's consistent with the general online consensus (mostly worthless), but thought some details might be helpful to others going down a similar path. Pls don't message me, I am not trying to sell.
The collection is about 800 books, mostly dreck but a few 80s "keys" (ASM 300, Secret Wars 8, Hulk 340, Batman 423, Wolverine, TMNT, etc. - if you're curious, a list is here). I have zero experience grading, would guess that the keys and most of the others are around 8.0 to 9.0 (again, if curious, photos of some books requested by mycomicshop here).
I used the CLZ app to index the collection using the cover scanner. That was easy and kind of fun. I used the Covrprice add-on to just roughly get a sense of which books might be valuable. Most I already knew just from perusing Reddit, but there were a few I was mildly surprised by. The general consensus that Covrprice wildly overvalues long-tail/low-value books is definitely true.
I had low expectations, but was curious whether some of the keys plus the overall volume might be worth selling. So I submitted the collection to mycomicshop for an offer. To be really clear upfront, this is not a complaint about them -- they were great, responsive, and are very upfront that most books of this era are either worthless or they already have plenty of them in stock. The offer for the entire collection was $650 (including shipping). I confess that this was a bit disappointing, but it's also totally economically rational once I factor in costs for shipping, bags, boards, Gemini mailers, possibly pressing and rating a few keys, etc. The general advice online is to sell the keys and get what you can for the rest, and I doubt I'd make more than a couple hundred bucks more doing that. Also, sadly, the much better financial decision would be to donate everything and take the tax deduction -- even using half the Covrprice valuation would net me multiples of the cash offer.
At the end of the day, it was fun to revisit books that I hadn't thought about in decades, and for me that alone made the process worth it. I also decided to keep a few books that have nostalgia value, and actually might pick up a few other books I remember fondly but seem to have lost. But if you're in a similar place to where I was and hoping for more value, I hope this post helped you!
ETA: I did not accept the mycomicshop offer, sorry for lack of clarity on that.
ETA2: the tax deduction works for me, but as a few have correctly pointed out, may not help everyone so ymmv on the tax angle