Trading for duals is usually easier than buying them because they can be pretty expensive online but you can often find people that don't play Type 1 that had them stuck in their binders after they rotated and may not know that they've appreciated in value since then.
I've noticed Extended players often consider them $10 cards. I say "acquire, Brock, acquire." I'd say trade away UD Masticores before they depreciate (both the new dude and the imminent rotation, plus the banination of the entire Tinker deck, assure that Masties aren't long for the $20+ category).