If you can talk a photo finisher into selling you a short roll of Blue Max film splicig tape you will be in heaven. My full roll cost $20, and it is several life times supplies. Its adhesive sticks well to film base, and to almost nothing else. It is waterproof, and stays in place thorough processing solutions too.
I addition to using it to load bulk load film to the cassette spool, I use it to join 120 films end to end to load on a Paterson reel when I am processing c-41 or E-6, and want to minimize the number of re-uses of the chems through the tank, where they get aerial oxidiation, while processing the rated numbers of films