a crash tested system is only bolted through the floor with spreader plates, not exactly rocket science, IMO I think you are paying for the fact their system has be crash tested, the they have had to spend many thousands doing that.
If you really want a crash tested system, you can go to Pure2o, an ionic company, and get the ionics crash tested tank fitted, but they will match the price of other company's non crash tested systems, at least the used to.