How much should one be paid for model making

I have been assigned to make 5 models of Logs (tree trunk) out of foam , the material cost to be taken care by the concerned company which does exhibition design. just wondering how much should i be paid. the dimensions of logs are 12"X30".
Any insight would be of great help.
vkdw

experience level?

time frame?

level of detail of the trees?

type of finish?

location?