What are these old smoke detectors worth?

Flea Market
1

Fyrnetics Lifesaver Model 0908 Smoke Alarm with Hush Control and Safety Light
Pittway / First Alert Smoke Alarm Model SA76RC
1990 Pittway / First Alert Smoke Alarm Marked Model SA81D On BOX and marked 83R On Dectector
1984 First Alert SA80FCSmoke Alarm

2

I can’t give you anything exact but those are all very rare: just the same though collectors don’t have all the money in the world, so please be moderate when you price them.

3

You can always donate them to various fire museums if no one buys them on eBay.