Proxy service with fixed IP

Can anybody sugge开发者_开发问答st a proxy IP service with a fixed IP address?

Google App Engine does not support fixed IP addresses. To verify certain transactions, I have to query my payment provider with a fixed IP. I have to configure a fixed IP.

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I use gAppProxy on appengine as proxy server, but appengine outgoing IP changed 3 times in 10 minutes, so that some website will shut my logined session