ya know this is gonna be a bit biased, but i'll try to do my best to keep it fair.

Fee Comparison

*Mercari has buyer fees, seller fees, cancelation fees, ...
**eBay's fees stupid complicated. If you have 20 minutes to kill, be my guest
**Facebook Marketplace

*** Facebook Marketplace
**** didn't wanna

add asterisk for facebook marketplace and mercari base rate (40 cents and 80 cents?) also add asterisk for ebay sliding scale of percentage
explain how fees for each work below
maybe also talk about craigslist and facebook marketplace local - recommend that route if selling local becaues avoid fees entirely