The level of protection will depend on what is in the aerosols. Non-flammable contents and non-flammable propellant is the least (fire) hazardous, whilst low flash point contents and propellant (eg hair lacquer) represent a 6-8 ton firebomb awaiting ignition. There are several spectacular videos on the Net of fires where aerosols have been involved and a simple search should be enough to frighten you! £60 seems negligible when set against the cost of the loss of a business. Your fire insurers will have an opinion.