I do have some first hand experience in this regard...
Generally speaking an authorized dealer for any particular manufacturer can discount the MSRP of a brand new item by no more than 20% (and sell as new for MSRP-20%).
If you then wish to sell an item (in excellent condition and within two years of newly released) back to the dealer, the dealer will typically offer about 45% less than MSRP.
If you look to sell privately, expect to get around 30% less than MSRP.
If the gear you're looking to sell is in poor condition and/or is very old (with respect to when it was manufactured), all bets are off and other variables such as vintage, market demand and phase of the moon come into play.
Generally speaking an authorized dealer for any particular manufacturer can discount the MSRP of a brand new item by no more than 20% (and sell as new for MSRP-20%).
If you then wish to sell an item (in excellent condition and within two years of newly released) back to the dealer, the dealer will typically offer about 45% less than MSRP.
If you look to sell privately, expect to get around 30% less than MSRP.
If the gear you're looking to sell is in poor condition and/or is very old (with respect to when it was manufactured), all bets are off and other variables such as vintage, market demand and phase of the moon come into play.