I originally had a Nottingham Tracer 3 (MM) on my Spacearm which I sold. In retrospect, wish I had kept it. It was a fine cartridge. MANY folks use a Dynavector 20X on the Spacearm. I tried one and it wasn't as dynamic as what I sought. I tried a Dynavector 17D Karat and found it a wee bright in my rig. Could have been my other components and speakers, though. I tried a Grado Statement Sonata once and found it too heavy and it did not complement the table or arm. I considered once a Benz LO4 but was dissuaded from doing so by my dealer.
Finally, I used a Shelter 501 MkII and it sounds fantastic on the Spacearm. Concerns of using the Shelter with a unipivot arm are not a factor in the case of the Spacearm, at least as far as my ears told me. The 901 also sounds fabulous with the Spacearm, but is out of your price range.
I usually do not give suggestions based on something I have not heard myself. However, I recently sold my Spacearm and the buyer has tried a number of cartridges and is thrilled with it using an Ortofon Kontrapunkt.
Good luck.
Finally, I used a Shelter 501 MkII and it sounds fantastic on the Spacearm. Concerns of using the Shelter with a unipivot arm are not a factor in the case of the Spacearm, at least as far as my ears told me. The 901 also sounds fabulous with the Spacearm, but is out of your price range.
I usually do not give suggestions based on something I have not heard myself. However, I recently sold my Spacearm and the buyer has tried a number of cartridges and is thrilled with it using an Ortofon Kontrapunkt.
Good luck.