If the old one is cheap and works, and if you don't need any features it lacks, you might as well save the bucks.
FWIW, I just bought a Clipper Creek HCS-40 with JuiceNet add-on, as sold here. It's supposed to arrive on Saturday. This unit is way overkill for a Volt, but I wanted to future-proof, and I'm also a bit of a data pack-rat, so the JuiceNet features appeal to me. (Of course, Juice Boxes have the same network features, and modern ChargePoint units have similar features, too.) As near as I can tell from my research, there are a lot of good EVSEs out there, so it's hard to go badly wrong, with the caveat that you might need specific features. (Mine's going outside, for instance, so I wanted the best possible weatherproofing.)
I bought the plug-in version of the Charge Point level II charger from Amazon in 2015. Didn't like the idea of having a charger hard wired. When it arrived, I found the stud to mount it above my 240 V plug, drilled the holes, put in the screws, and had the charger installed and working in less than half an hour.
This charger that I got new last year has WiFi and based on my location, knows the utility rates, etc. I can look at the trends and see that I generally use about $27 of electricity per month. On my phone I can see every time I charge, how long, and how much it cost to charge as well as the monthly trends. I spent extra $ to get this WiFi capability with the level II charger and think over the long run, it is worth the extra $.
I'll echo what srs5694 said - the used one will likely work just fine, and you're more data-hungry (as both srs5694 and myself are), you can get the add-ons to measure your charging stats. I was intrigued by the JuicePlug device, but hadn't really looked at it, since I've already decided to buy a L2 EVSE with good data measurement capability.
A forum community dedicated to Chevy Volt electric car owners and enthusiasts. Come join the discussion about hybrid performance, modifications, classifieds, troubleshooting, maintenance, reviews, and more!