The vintage Soma would benefit from more photos, but probably comparable to the Univega, both Japanese bikes with limited heritage and market share.

+1 to Thrifty Bill's comments. If the outside of the bike looks tired and dirty, do you think the moving internal parts are going to be better? All the dirt around the fittings, probably means a lot of dirt in the bearings. You can count on spending at least $100 if the cables need adjustment and lubrication and the bearing sets need cleaning and replacement.

I have acquired and resold many bikes in the last two years, mostly quality brands including Trek, Peugeot, Raleigh, Specialized, Motobecane, Gary Fisher, Bianchi, and Bridgestone. 95.5% of the bikes show no evidence of bearings maintenance since they left the factory in the 70's-90's. Ironically, a keeper, a ratty looking 1986 Raleigh Competition USA with bad paint on a revered Japanese built Reynolds 531 frame, had the freshest grease in the bearing races and cups. Today, I broke down a clean, lightly used Specialized girl's MTB, and the front bearings were bone dry, so there is always a surprise.