You probably know about these already but for specialist stuff go to Der Produkte Katalog - Bächli Bergsport AG in Oerlikon, they are not cheap but in my opinion not more expensive than the equivalent items in UK or Germany.

For light camping requirements Obi sell portable gas stoves, chairs and blow up mattresses. Landi also sell portable gas stoves and, IMO, they will be far cheaper and far better quality than you'd get most places, they do camping chairs too but I haven't seen air beds there. You'll need one of the larger Landi stores like the one in Pfäffikon ZH.