neck ties, dressing gown cords, scarfs, that sort of thing.
Neck ties for example you can get for less than the price of a can of drink in a charity shop and you can get shit loads of them.
If you wanna spend a little more money then its not even that much more expensive to buy rope by the meter at a hardware store or something, you dont want anythign too rough or itl hurt.
As for the tickling part, take your time, slowely arouse your lees nerve endings gently before you get stuck in, allow good time for the mental comfort barriers that may be in place to be broken down and then once your both fully comfortable,... wreck her 😉