I haven't really heard of chameleon "trades" before, nor do I know how that would work out.
My question is why do you want to trade? your "plain" veiled costs less than a high quality translucent, which means you would probably have to put money on top or settle for a low quality translucent. With a low quality one, I doubt it would be worth the headache of shipping your animal, receiving the new one - and then dealing with any problems that arise on either parties side. Paying to ship your animal and paying to have one shipped to you would probably be worth your chameleon alone. Considering that most carriers charge at least $40.00 dollars for overnight shipping. Standard shipping is never an option for a live animal.
If you really want a translucent, why not just buy a second chameleon? each one is different and wonderful in his/her own way. If this sounds like a good idea, then you should check out FL Chams - they have some really really nice high quality ones.
http://flchams.com/inventory_all.asp?id=1036&cham=Veiled Chameleon Morphs For Sale
The thing behind the foot is called a tarsal spur, and yes having one means it males. No spur means a female.