Can't beat that price! Funny though...you'd think since it was a garage sale and somebody was interested, they'd say something like, "well it isn't really for sale, but I can let you have it for $20...and it still would have been a bargin!
Now, even though it's in good shape, after you clean it up, you might want to clean all the corners well and add a bead of silicone (for safe measure...ounce of prevention theory).
As for a hood/light, I was just pricing them for my old 29g and best I found on-line was $40 plus shipping (didn't find at the LFS, but I got side tracked and dragged home the 60g!
Since you have glass cover for the top, you could get a fairly inexpensive florescent light and using 1x4" and some thin plywood or Masonite, make a DIY cover? (just a thought)
Anyway, great deal....good fortune.