Those should be a snap buy (or snap grab, since they're free) to anyone nearby. Gassers are very comfy for sitting on a long time, with backs that have a slight give/rock to them, and if all the chairs are similar to the one in the photos, the foam in the seat looks to be in good shape.
If chairs are stacked more than 3-4 high, the foam will compress on the bottom chairs, but once unstacked, the foam should eventually come back to shape. I have a few gasser-like chairs, and use a piece of hard cardboard on top of the seat to help minimize compression from the bottom of the chair legs above when stacked stacking.
