I just have a question about whther we are able to sell or give mods from one character we may own, to another? Like for instance, if you happen to have a Wild Weasel Unit for your Red Horn, and you upgrade it to a Dark Horn, which can't use the WWU, could you donate the WWU to a Zoid one of your other characters may own that can use the WWU? Like an Iguan or a Gunsniper?

I'm... not all too sure of that. That's more Ritter's department, and he's gone for a week. Though my mind is telling me no for this question, I'm going to ask you to wait for Ritter to come back.

Would you just give the mod to somebody else's character? Of course not. Similarly, transactions between two characters require more than a token monetary exchange. Unless the characters are really good friends, in which case it could be just a hundred or so credits. But a character selling a Gunsniper that had the WWU and purchasing a Red Horn would not have to purchase a new WWU.
Standard costs would be somewhere in the region of half of the current price.