Wizardry 1-6 work in DOSBox, and only in DOSBox. Wizardry 7 (floppy & CD versions) works in and only in DOSBox. For these versions, you'll need to limit the cycles in DOSBox to prevent divide overflow errors and sound glitches. Wizardry 8 works perfectly fine in Win7 straight off the disk.
No clue about Wizardry Gold, but it was designed for Windows 95 so it will likely have more and different issues. It's also a vastly inferior version of CoDS, so it should be avoided if possible.
However, I'm not sure what you mean about buying them. At the moment they aren't for sale anywhere digitally, so your only option for purchase would be old boxed copies.