Life rafts
If you do buy a life raft, it should be inspected/certified every year, over pressurized every 5 years (i.e. hydro'ed) and after 10 years they are usually recommended to be tossed out and replaced due to the harsh conditions they live in (Hot/cold, humidity, salt, etc.)....... Not to mention, if in a hard case on deck, you'd want a hydrostatic release with weak link because if the boat sinks in 30 seconds there is little time to be fiddling with releasing a raft or grabbing a 50 pound sack and deploying a raft (usually at night, in 40 knot winds in 15 foot seas). I've heard of a few cases where the valise raft was deployed but blew away in the high winds rendering it useless as it was not tied off before triggering (!).
Also, I heard of a valise raft stowed in a sail boat's lazzie that some how triggered. It took the guy a minute or two to figure out what in the hell was going on (loud hissing noise, cracking fiberglass), a minute to grab a knife and puncture the raft repeatedly. But by then it literally blew the back end of the cockpit and transom off!
Also, make sure you research the type of raft you buy (double inflatable bottom, double segregated tubes, canopy, type of supplies, etc) as when you need it, you'll REALLY be happy you picked a good one. Winslow now makes a raft that doesn't stink like rubber, which usually makes 90% of the occupants start pukeing, has a sky blue ceiling, tan tubes, and is a genuinely excellent raft (always highly rated by Practical Sailor and many other reviews I read). They modified their FAA approved (Aviation) raft for marine use which I saw at a boat show and was impressed with it (BTW, no affiliation with Winslow)
http://www.winslowliferaft.com/
Here in San Fran, raft rentals are quite common, check around, ask the commercial fishing guys or ferry operators...they know the good companies that do quality work. Here in San Fran it's Sal's Inflatables and Coastal Marine.
A quick check found this Winslow rep with rentals in Puget Sound:
http://www.westpacmarine.com/
John M.