Scripting questions

[iDigzy]

I am having trouble with params. I am really not sure how to phrase this question I will try the best I can. Ok so I was making a small shop menu, and I wanted to have the npc trigger the shop menu. In the npc trigger to the shop it would contain the price and other params. I want to be able to use these params in the weapon it triggers and for example make the price.txt = the param price. I also am confused on how the script will know what the trigger is and to make it so it only uses the param of that trigger. For example, if you had more than one triggers going to a weapon script and you wanted to make a gui txt say param 3, how would you be able to tell it to only use param 3 of a certain trigger? I pasted my current script also, as I''m pretty sure I did not phrase any of this right D:
Npc - http://pastebin.com/uiBWRAUL
Weapon - http://pastebin.com/W87eGjhX