I think what you're looking for is either prohibitively expensive or kind of unreasonable. At the very least a giant pain in the ass to manage.
Now, if this is just for account creation itself, then you only need the IP for 5-10 minutes tops, right? That means you're never going to use that IP again. Even if you used a private list of scraped/hunted proxies like proxygo's, you'd still have to keep a list of which IP you used when in order to keep from repeating yourself, otherwise the whole system is invalid anyway. And after a few months (that's if you're EXTREMELY lucky) you're just plum going to run out of a decent amount of IPs no matter what, as there just aren't that many available to use if you're never repeating.
If you go with a private server proxy solution like packetflip, you'll have to repeat IPs, but it's a lot easier to process and you never have to worry about downtime. Instead of continually inputting all the proxies to whatever script or program you're using, you can just rig them up once and set it to random select (plus easy geolocation and a bunch of other features). At least then you don't have to continually modify your script and pay out the ass for new IPs every day that'll eventually dry up.
Either way, pain in the ass.
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