Hard to say but the front derailleur looks like it may be a SunTour Alpha 3000, which would indicate a 1987-1988 model somewhere around the crossover between entry level and mid-range, depending on the frameset. Binchigirll can probably ID the model and tell you what the tubing is. I also noticed that the pics themselves are dated from almost five years ago, so the condition could be worse than shown. AccuShift from this era wasn't great shifting even when new and compatible parts can be hard to find but at least it should have an index option. Assuming pics are reprersentative of the condition and everything still works, I wouldn't go over $50.