How long is a piece of string? It all depends. If you want compatibility with other vehicles, you'll want to install an EVSE (Electric Vehicle Supply Equipment) that uses the J1772 standard (and connector), which is pretty much everything that's on the market other than the Tesla systems. Tesla includes a J1772 adapter with every vehicle, so you can use these EVSEs with Tesla vehicles.
I personally like the OpenEVSE solution. This is an open-source EVSE. While you previously needed to purchase and assemble OpenEVSE kits, they now offer pre-assembled units.
Another common option is the systems from ClipperCreek. They have been in the EVSE for a LONG time and have excellent customer support. You can find many stories here on TMC of ClipperCreek working to resolve any problems that arrive. I personally had them advance ship a replacement for a compatibility issue on my LEAF when charging timers were active.
If you want access control and the ability to bill people that use your charging station, you can look at the ChargePoint and WattZilla product lines. Both of these products offer access controls and billing options.