Material life depends on usage and environmental conditions etc.
Dibond should last almost indefinately.
Foamex has an 8 yr outdoor life (at best) and is PVC , see PVC properties for the life span.
Magnetics will last a long time as well , depending on useage (im not sure about whether the white will yellow or discolour over time, moist likely depends on brand) , 3yrs would be reasonable?
Correx life will be a function of whether its uv treated or not but suffice it to say , its not really meant as a durable life long product and I would only use it on real cheap signs with under 3 yr lifepsans and that would be under ideal conditions.
Banners are by their very nature , short term , wind etc will affect them. I wouldnt give more than a 6 month warrantee on any banner used outdoors in a windy location – perhaps if you feel lucky , a year.
For quality signs , use quality materials and charge accordingly , we use perspex a lot for most of what we do.