In reply to cb294:
I have an Ally 15' folder, and its excellent, a proper canoe when assembled. However, its somewhat more expensive than £500, even second hand.
I agree that many inflatables are rubbish, but some are different beasts, including the said Palava. I know of people who've done serious expeditioning in Scandinavia using them, both on open water and tight, rocky, whitewater. The Palava actually weighs just under what my Ally 15' weighs (17.5kg v my 18-20kg depending on solo or tandem seating). It catches the wind more than a "hard" canoe, but so does the Ally, a large factor of which is the low weight. Learn to paddle them well, trim them properly etc depending on wind direction, and they have a genuine place in the paddlers' armoury. I agree that cheaper inflatables are exactly as you describe, and would have agreed with you entirely were it not for time spent paddling borrowed Palavas in the last year or so. The biggest disadvantage of the Palava over my Ally folder is the lower capacity for camping gear, but this wouldn't be a problem solo.
Sorry, getting off topic!
Another "different" angle you could take is to kit yourself out with what I guess would be thought of as bushcraft kit, for comfortable camps all year round - fireboxes, axes, skillets, dutch ovens, big tarps, poles, tripods, etc, etc.