lol 3k IPs funny, funny
If you want to buy such a high volume, you might think of becoming a registrar.
Normally, you get per server (vpn/dedicated) maximum 254 IPs in the same C-class, in a worse case only a subnet with say 16 IPs. By this way, you pay ~ 4000 monthly for your server and IPs at least.
If you wait a little, IPv6 comes and you can spare so much money: You can have easily subnet of 2^32, even 2^64 IPs is possible for 0 $.