Cutting out the S and S2 leaves the SP (vintage and reissue), S3 (vintage and reissue), and S4 (vintage).
You could probably get a vintage user SP with 50mm lens for around $1,200 - $1,500, but prices go up rapidly from there in accordance with the condition. The reissue SP is sold in the SP Limited Edition kit along with a 35/1.8 and $4,000 is about right for that.
For a vintage user S3 with 50mm lens I'd say around $750 - $1,000, and again prices go up from there in accordance with the condition. Reissue S3 bodies (silver version) are selling for around $900 for a used sample to around $1,100 for a never used sample. The black version goes for about $400 - $500 more.
You're probably best off not bothering with the S4 as its the same camera as the S3 minus the 35mm frameline and frame counter, but commands a premium because of its rarity.
Goold luck tracking something down!