Thanks to Albconde’s massive efforts, the ZX Next core on the MiSTer FPGA has improved so much that one does not really need to own a Spectrum Next computer to fully enjoy the system any more.
Here at Ultimate MiSTer we have tested a number of commercial, recently released games for the system and all of these worked without any issues. The ZX Next core can be obtained by running the usual update script on the MiSTer FPGA system.

Using the ZX Next on a MiSTer FPGA setup holds a number of advantages, including higher integer scaled resolutions (of up to 1440p in 4:3 aspect ratio) and a better choice of CRT shaders.
If you still wish to own a stand alone Spectrum ZX Next computer, here at Ultimate MiSTer we sell the N-Go variant, which comes with an identical motherboard in a very cool looking case reminiscent of the original Sinclair ZX Spectrum design. At Ultimate MiSTer one can find also stock of hardware and accessories for original, vintage Spectrum computers.