They use rare earth permanent magnets and don't offer the resolution of superconducting magnet NMR, but they are much smaller and cheaper (tens of thousands of dollars, new) than superconducting units or the even older resistive electromagnet NMR units. The first one I saw was from picoSpin, which has since been acquired by Thermo Fisher Scientific. I think that there are multiple vendors now. Here's a current picoSpin unit:

https://www.thermofisher.com/order/catalog/product/912A0913