Assalamualaikum MediaMove buddy, price is something we must be considered before deciding to advertise through outdoor advertising media. Diverse prices certainly can make the client confused. Do not be obsessed if there are some premium spot with lowest prices, because the lowest prices mostly give an impact on the quality both of material and the safety element
The safety element is not only based on the installation, but as an advertiser we must pay attention about the environment, if we overriding material from outdoor media it will certainly affect the safety of the environment around the spot.
Try to choose a price which is quite competitive by comparing the advantages and disadvantages of the services offered by the advertiser provider agency media buying.