Old Singers and other machines, treadles and otherwise do have value. Just not the over inflated value some people try to attach to them. They are far from boat anchors, just not real collectors items unless they are truly mint with all their accessories and attachments.
I've rescued a couple I would never have bothered with because I thought they'd end up in the land fill. Turned out they're both good machines.
Don't be too critical about that Pfaff tomorrow. If it's in any shape near good grab it.
Joe