What components I have to buy?
If you write them with prices, I'll be happy.
Hmm I have to buy active RFID reader, it's good. But I don't know how can I determine it works with Arduino or not.
My problem is about which devices is suitable for using with Arduino.
What have you found in your google searches so far?
You will have to say what device first before anyone can say if it will work with an Arduino.There are many different types of reader.Also 870-950 MHz is not the only frequency you can get active RFID tags, maybe some of the others might be cheaper.
if there is a ttl, it can be used with Arduino. Am I right?
I just want to make car parking system. So it has to read the tag 3-4 meters away from barrier.