I saw a Suntour aero cable stop adaptor go for $120 on eBay about 2 years ago. The only one I've ever seen for sale there.



There was also the Gipiemme Aero shift lever adapter



There are a few threads here on how to modify a Suntour Symmetric body for cable guides. If I recall, the threading might have been odd, so if you go this route and need to buy one off eBay, make sure it has the bolt.