These are sellers I've found on eBay that regularly sell Gundam Wing stuff.  A indicates I've done business with these sellers and was pleased with the results.  The others I've never dealt with. *

A lot of these names you should be familiar with, as they are also popular fic writers.  

eBay

qshineq  

babaca 

chibishop

dissolved (baby_pen)

guenwhyvar (Ash)

heeros_ferret - commissions by the person who runs H.I.N.T and Invincible

jade9999 

katsunomiko

marmaladegirl 

mobiusklein  

saishi-fablespinner - fablespinner has quit selling djs on eBay.  She now sells them from her own site, here: http://fablespinner.theshoppe.com/ 

talya_firedncr 

y-con - all sales go towards yaoi-con

*Remember - just because I was happy with the results does not guarantee that you will be.  I will not be held responsible if a transaction with someone on this list leaves you unhappy.  I'm just pointing you towards the seller, not telling you to buy from them.  There, now I've covered my ass ;-).