$450 is not a bad price, depending upon condition.
Offer him $350 cash, and see what he says. If it's in a shop, he probably has about $300 in it, maybe a little less.
America needs to understand that our troops are not 'disposable'. Each represents a family; Fathers, Mothers, Sons, Daughters, Cousins, Uncles, Aunts... Our Citizens are our most valuable treasure; we waste far too many.
