If it was me, I do not like the prospect of used keyboards, especially ones that are more than 3-4 years old. Even though the old Razer keyboards used genuine Cherry switches, which are amazing, it would be better to get your money's worth and buy a brand new one that will last for 3-4 more years. With a keyboard that old, there is no guarantee that one if the switches won't die out sooner than a new mech keyboard would.
There are quite a few keyboards on sale still, so I would buy a new one. IMO it's only worth getting a used keyboard if it hasn't been extensively used. The Ultimate 2013 was a good keyboard, but many of the newer mech keyboards today just do the job far, far better.