I was looking at buying a Proxmark, but one of my bigger interests in parking tags. What kind of RFID tags are commonly used in parking badges, and is that kind programmable with a Proxmark?
Unfortunately, the Proxmark won't work for a lot of them.
In the past parking systems I've used, they've all been 900 MHz UHF systems. This is necessary to read at the >2 meter range between your windshield and the reader. Some have been EPC and one was based on toll collection systems, ATA.
You'll find that these UHF systems are a lot more expensive than 13.56 MHz HF systems, with costs easily reaching $1000.
I think you’ll have to do research to understand what kinds of parking system tags are available for you to study. The nice thing about the Proxmark is that it can understand several different frequencies, and dozens of communication protocols. You can even issue a command to discover an unknown tag type, and it will do a fair job at guessing it.
What the Proxmark can’t always do, however, is recover the encryption keys from the cards. Without the key, you won’t be able to read or write tags usable by that system.