Before Choosing a Proxy Host, keep these things in mind -
1. The Proxies need lot of CPU power and Memory as well as bandwidth so make you get as much as of these. Disk space doesn't matter.
2. Always go for Dedicated or Virtual dedicated server. It may cost you $100+ but its worth it. Other thing that you can do is, initally you can share someones server for first month before moving out.
3. Check the reputation of the host, preferably at http://www.webhostingtalk.com/
