I made the mistake of trying to pay for a VPN service with Paypal while using Tor browser. Paypal said the transaction had gone through. But my bank statement said otherwise. I haven't validated the purchase with the email link sent by the VPN service and do not plan to. Have I blown my anonymity? Have I alerted anyone to my I.P. address and identity as a Tor / VPN user? If so what can I do about this? Is it worth paying for a VPN service by regular means? I do not do any illegal downloading and am a little confused about the advantage of a VPN over and above Tor.
I do not believe you have blown your anonymity within the Tor network. You do not have an IP address for yourself but rather the IP addresses of all exit relays is shared among all people in the Tor network. The Tor Project provides a concise introduction to Tor on this overview page, take a look at it.
However, your VPN identity is a different story. If you use a credit card, which I assume is yours, at the very minimum the VPN provider knows your identity. You cannot know if they keep that information safe. The information may be stolen from them or shared with third parties. Even if you'd pay in a different way, the provider is going to know all your doing using its service. It knows your real IP and sees all traffic, just like your Internet provider usually does. Moreover, there are no guarantees whatsoever that traffic flowing through a VPN is more secure/anonymous than just using your regular Internet connection. Tor however is designed so that even the operators, volunteers spread across the world, cannot deanonymize you easily. It has technical measure to secure the network as well as the browser which everyone can inspect. See .
I'm sure there a valid uses for VPNs, like avoiding censorship. But as general rule, a VPN service may be safe but there is know way of knowing and Tor has flaws but has provable security guarantees that at the very least make it hard to deanonimize you.