No experience with aftermarket, but according to partzilla you can buy New OEM still for around $46. 85-87 TRX250, 85-87 ATC250ES and ATC250SX all interchange (same part number).
https://www.partzilla.com/product/ho...b885bb0fae7c2b
The rubber tip is available too.
https://www.partzilla.com/product/ho...b885bb0fae7c2b