when I'm selling stuff I typically take off 25% for new in box gear, otherwise return to dealer for full refund if you want top dollar. For gently used equipment I like to get 50% of what I paid.

I'm slightly more optimistic with my own gear. Unless it has been damaged or heavily worn, I normally try to get around 70-75% as long as it's relatively new and not more than a year or so old.

I do the same, 50ish% is fair for good quality gear to me. I usually ask around 60% so there is room to haggle. I wouldn't even comment on a used 200 dollar item for sale for 150. As hard as this stuff is used, even when meticulously maintained, the risk is too much and I'd rather just buy new. I maintain my gear to an OCD level that's ignorant because I have the spare time to do so with my work schedule and I sell for 50% because that's just what the market will take for a reasonable quick sale.