I bought a Leupold on ebay that was in mint condition for $150 it retails for $399 I used once and noticed it would fog up in the mornings,I missed killing a huge 10 point cause I couldn't see it.

Rather than contacting the seller because 8 months had gone by, I sent it to leupold to get it fix.
2 weeks later they sent me a brand new one.
Most good scopes have a life time warranty.