The Rega-refurb list of companies seem to grow by the year - so scour the web to find the one that fits your budget
I initially had the Cardas tonearm upgrade applied to my arm and it was a significant upgrade.
After a few years i decided to completely rebuild the TT, which now only has the power switch and dustcover left over from original components.
The arm I replaced with a Series 3 (classic) tonearm from Audiomods, which is just amazing and uses a Rega Arm Tube - highly modified.
They also do arm upgrade kits and a one piece harness
So it really depends on how far you want to take the upgrades
Regards...