I've been very lucky selling obsolete miners.  There seems to be a huge market of people on eBay who have no idea how much they are NOT worth.  Sold Two S5s for a couple hundred bucks each when they were negative profit.  Last week sold two A2 110MH Scrypt miners for more than I paid a year ago.  Baikal Minis are re-selling over $1000 right now.  I even sold two SHA-256 USB thumb miners (U1 and BitFury Nano) for $35 each three months ago!

Buyers seem to enjoy small personalizations that add value like quiet fan mods or additional rubber feet.  I prefer eBay for the buyer and seller protections.  Be sure you document everything.