Don't know if it advertising other forums is legal in DP, but namepros.com usually has some people selling bulk domains. dnforum.com is also a nice place to look at.
I think you may be looking out for ResellerClub. They are wholesale domain resellers that have gained quite a good rep.
There are several sites in the internet the offer bulk registration. You can buy in godaddy and get great discounts.
We offer bulk registration at economicaldomains.com - pm me with more details and I'll give you a great rate and free privacy protection for all.
There are many number of sites who offer bulk Domains registrations and also give cheap prices while registering these Domains.Best is Godaddy who offer cheap prices,offer bulk registrations,provides coupons to reduce prices and are used by many number of people woorldwide over the internet
OP probably have meant "at bulk prices". but the truth for many registrars (such as godaddy) the retail price after coupons is actually cheaper than bulk price they advertise