I know your probably a little concerned about buying a used charger vs. a new charger! Trust me you can't go wrong when it comes to name brand chargers!
I've owned a few chargers in my time and right now I own 4 chargers (LRP and Novak) and they are all used! I've asked the racers why are they selling their charger and every time it's been they are upgrading to bigger and better and there was nothing wrong with them. They just wanted something with more bells and whistles! As for us we just want a good reliable charger that does the job!
If there is a situation where the charger dies on you, don't worry, both brands have an excellent warranty and no reciepts are necessary. I actually had two go bad, one LRP and the other the Novak. One charged me $20.00 including shipping to fix and the other was a no charge and I didn't even pay shipping. One even let me up grade to a better charger for $30.00 with the full warranty as if I bought new! So if you race or practice at a local track there is always somebody selling used chargers and as long as it's name brand you won't be dissappointed! Just ask around and I don't think anybody will disagree with me!
Good luck shopping and have fun racing!!!