Wrong forum. You want to pose this type of thing in the Trade Values thread.
But, I've never seen 2/20 dual leach gloves. I didn't know they could spawn that way (granted, zon is the class I've played least).
I know that if they had dex or life on them, I'd never sell them.
Your target buyer is someone that just cannot fit mana and life leach into their gear. Maybe they want to use 2 skill rings and they aren't using COH. The least valuable part of the gloves is the life leach for most. If that was high dex and you had life, you'd have something indeed.
I can't price them as in all my years I've never dealt with gloves like that. Don't sell them at your first offer. My gut says pul+, as most people are going to want dual stats or big dex on gloves at least.