Is that true? I see ads every day from KEH, Geo Ury, B&H, Adorama, etc. saying, " call us for a quote on your used gear." Sounds to me like they're buying and not just taking in on trade.
Actually, given this question about trade vs buying outright, I have a proposal for the OP that would let him feel that the dealer was being more than and that he was getting max value for his lens:
~ Agree to buy one of those rare Canon 1200mm f5.6 lenses from B&H ($125,000 last time I saw they had one!)
~ Offer the Canon 70-200 2.8 mkI in trade.
~ I bet they offer you $1500 in trade-in value
~ They're happy - they sold a $125k piece of glass!
~ You're happy - you got what you wanted, indeed more than you expected, in trade!
~ Downside = You need to purchase another seat on the plane back to India!
I am talking about the shop that he works at, BH, KEH and the others do straight buying. Many smaller shops that dont have the bank account to buy things will put them up as consignment.