Finding one source with that many available IPs would be difficult. I recently made some inquiries on a similar matter. I wanted a huge pool, but I wanted strong data center type proxies. Allotting that many proxies would tie up a LOT of servers/IPs and most companies can't, or won't do it. You'd probalby be much better off piecing that together by buying 500 here and 500 there, that type of thing. I'll be honest I was looking for around 10,000 IPs to use, so you may have an easier time with 3k, but I think you'll still be much better off piecing them togehter here and there.