Another option in your neck of the woods is an innovative Anchorage-based outfit called Alpacka, which makes inflatable rafts specifically for wilderness travel. These are tough, versatile little dinghies that should serve you well on the kind of trip you're planning. Price-wise, too, they come in at much less than more specialized inflatable kayaks. Try the Yukon Yak ($775; www.alpackaraft.com), a snug little boat for six-footers thats been known to haul MTB rigs. Beyond the price, the weight here may be the deal clincher: under five pounds! Good for the water you describe, though not recommended for more roiling Class III-IV stuff.
Now for the hard partthe transportable bike. Probably your best bet is to go with something like the Dahon Flo ($2,000; www.dahon.com), a steel hardtail mountain bike that uses the Ritchey BAB coupling system, which allows you to divide the frame into two parts. It fits into what you might think of as a "medium-size" suitcase, and with a packed weight of about 25 pounds is easily carried around in a kayak. And, as a bonus, you have a bike that can handle most gravel/dirt roads, or even trails, which is likely what you'll run into on your ride home. You'll need to add a good-sized luggage rackJandd's Expedition ($65; www.jandd.com) would do nicelyand experiment with how best to secure the packed kayak onto it.
Cost is a factor, no question. You might consult with a local bike shop about the availability of kits that allow you to whack a bike frame in two, then use joiners to re-connect it. That way you could buy an inexpensive steel-frame hardtail mountain bike and do your own conversion.
In any event, sounds like great fun. Watch for bears!
Want to ogle all the gear you need before launching into a backcountry epic? Look no further than Outside Expedition in the Outside 2005 Buyer's Guide.