You pretty much have to watch all the eBays (USA, Germany, England, etc.) and they come up about once every month or two but sometimes there are long dry spells where they don't come up for sale at all. They sell for $50-60 on average. Sometimes $70. Make sure you get the 'little spacer' that goes under the headshell too. That part is always missing.
This headshell has an adjustable azimuth (the screw on the bottom back of the headshell). Which is nice but just another thing to adjust.
This headshell was used with the SR-838 and SR-929.
I was like you. My 838 didn't have the original headshell but I got one on eBay for $40 I think it was, from some guy in Argentina. Now that I have one, it's nice, but it wasn't really necessary. Any 'quality' headshell will work just fine. A good one would be the same 'looking' Sansui headshell in silver or black 'without' the azimuth adjustment, or...maybe even get an old Nagaoka! Or a new Nagaoka!
If you want the original headshell, watch the eBay(s) daily and you will find one. Don't bid on it until the last 20 seconds and throw down $60 and you will get it, probably for cheaper than $60. Maybe throw down $70 cause they don't come up often.
It is 'nice' having the original equipment. But there is nothing wrong with a $100 Nagaoka!! Old Nagaokas are super hard to find. Had a chance to buy an old one (1980) for $75 and passed on it. I wish, I really wish, I would of bought it. The new very nice ones sell for $90 to $110 about, but I really like the old ones.
The SR-838 is one 'great' TT!!!!!!!!!!!!!!!
Good luck and happy hunting!!