I resell everyday on Amazon, this year, sold 800items, avg profit $30 each after fees,shipping.
Yes there is commission, but on Amazon, things usually sell easier and at higher price then CL, and you also don't have to deal with phone calls, negotiations, no shows etc.
best part is that I don't even need to leave the house, not even to mail the items. (postman comes to me for free)
I could do it as well, but you always have to worry about returns or chargebacks. i don't ever have to worry about that. no shows have never really been a problem for me. and as for negotiations i always price higher so i am "nice" enough to lower it to my original price. you know gotta help with they're gas XD!