"Razorworms are just Mother Natures way of reminding you why it is important to man the walls." - True, but: PHR and UCM don't deploy Razorworms, and Scourge don't have lots of secondary machine gun mounts looking for target.
I've definitely used eBay to buy DZC - there's no stores that carry it in my immediate area. General wargaming forums might also be a decent place, if you feel up to managing that process.