I've got to say, handcuffs REALLY are the easiet (and safest!) way of doing self bondage with your hands. You just slap them on and they'll keep you nice and secure - and provided they're safety cuffs, you can get them off whenever you need to without too much time or effort.
You can get them so cheap as well - you can easily pick up a pair for £5. They aren't exactly big either, so I'm sure you'd be able to find yourself a little hidey-hole to store them in away from prying eyes.
At the end of the day, I'm sure there are lots of complicated little methods you can use to bind your own hands with rope or tape - but they take a lot of time and practise to perfect. I'd suggest you're best off just biting the bullet and investing in some cheap cuffs
