You can get IP's for $1 a piece at a few places still. Most of them will demand that you have 1 domain for every IP you request. Some will check to make sure they are valid, others might not. It might be worth investing in a large portfolio of the cheapest tld domains. In some cases then, the host (especially mainstream ones) may very well give you up to 25+ for free, with a managed server, assuming you tell them you have a large portfolio ahead of time. Then tinyproxy etc. needs to be installed.
I'm a bit confused by your question. But if you can get IP's for $1 or less each, get em!