I have a lot of experience selling brochures on ebay, probably sold in excess of 300. The highest earners were $32 for a 1959 VW brochure. I got $28 for a 1978 Firebird brochure, $35 for a 1976 Aston Martin brochure and it went to Japan! The craziest was a one page driving impression of a 1978 FORD DURANGO, yes Ford Durango which fetched $48. Reality is they mostly sell for a lot less. On average I'd say between $10 & $15. Most of my Canadian Pontiac brochures have sold for under $10. If you put them up for $15 I think you would probably sell them due to the age and condition you describe. Your best market is right here I would say.