A 240mm, 300mm, or 360mm plasmat lens would be a great general use lens. Any Schneider or Rodenstock lens like a Symmar-S, Apo-Symmar or Sironar would be good. These are largish fast lenses in Copal #3 shutters and were very popular lenses for 8x10 studio cameras. Because they were popular and the current demand is for small light lenses, the plasmats go for very reasonable prices--$300 to $500. Since they were mainly used in studios, they're usually in great shape. They're very sharp modern lenses that project a bright image on the groundglass. Also, very popular, the Kodak 14" Commercial Ektar is excellent and affordable. For about $250-$300, you can find a Turner Reich Triple Convertible that gives you three widely spaced focal lengths by using the complete lens or the single groups. I have a 12"/21"/28" version and it's a fun little lens.