If you're on good terms with your local film processing lab, they might be willing to part with/sell you a roll of the tape they use to attach film to leader cards. This stuff is tough, won't come off (as long as you attach correctly) when processing and best of all: easy to remove and doesn't leave any residue whatsoever.
Additionally, if you take a bulk-rolled/re-rolled C41 film to be processed, they won't have kittens and panic if they see you've used Scotch Tape (aka. here in Australia as "Sticky Tape) to attach the film to a spool.
I just bought a roll (at cost) for $AUD20.00 - it's also available through mini lab suppliers.