Good luck finding, let alone paying for, 500 adults. A typical price on a mix nymph package is 30-40 bucks for 100, which usually only includes a couple of adult pairs.
Clear, our dubias are coming Wed/Thurs...what size tub do you recommend for a mix 500? The breeder suggested a 66qt, but that seems a bit small to me, especially if you are running with 45gallons.