The Kevlar reference was indeed from SARA's own site.
However it didn't strike me as that odd, Kevlar isn't usually used in boat building for its "bullet proofing" properties - its normally just a strength / weight argument. Increasingly common in high performance sailing boats. Its used in some of the RNLI all weather boats (possibly all the current designs?). DuPont claim it has better damage resistance and fatigue properties. http://www.dupont.co.uk/products-and...omposites.html
I don't know why they specced Kevlar (or perhaps they didn't but specced a speed / size / weight that demanded it). All out speed is rarely a lifeboat spec - but lighter hull = more fuel can be carried = longer endurance. If damage was a concern the alternative would have been to spec two boats so there was a reserve - which obviously increases cost. As Chris says the Kevlar fibre isn't that expensive, but it is more specialist to work with and means the hull has to be epoxy not polyester. Even then the material costs alone wouldn't justify the price tag - but you do limit the range of suppliers who have the skills and equipment to lay up the boat.
Is it a "waste" of government money? Difficult to say. If we accept there is a need for a rescue boat of that size in that area then you might turn to the RNLI as the "reference design" for a boat of that type. It seems that an Atlantic 85 (carbon fibre based?) is in the same ball park. Many "independent" lifeboats have "made do" with recreational or commercial spec boats (including SARA). They may well have a better idea of the true cost of ownership of boats built to a budget and driven in demanding environments.