It really depends on the cues, what they are, desirability, who made them, conditions etc.
You can't put a percentage on how much to lose, or even mark up, and sometimes it comes down to availability with cues.
There is no set way to determine it.
Everybody had different taste in cues, and many cues are just too expensive until they hit the secondary market.
A 40% loss isn't uncommon with many cues purchased new at retail prices, and if you call the cuemaker to get the prices he charges, good luck selling them.
I have never called the cuemaker with pricing questions unless I intend to order a cue.
It is virtually impossible for me to make a deal with guys who say "the builder said the cue is worth $$$ " or "the Blue Book says the cue is worth $$$"
Maybe 20% of the used cues out there can sell for close to what the cuemaker tells them it's worth, and 10% that bring a premium.
Then there are the guys who listen to people in the pool hall... "I was told this Viking is worth $2000"
There is no reason to lose 15-20% if you don't have to, just depends on the cue, and how bad you want to sell it.
