Rob,
I’ve used vinyl electrical tape before and much prefer the rubber tape myself. Some people wrap the vinyl tape backwards so it doesn’t stick to the bark, but I still like the rubber tape for the stretchy-ness. Temflex also breaks down in sunlight, so it doesn’t girdle and removes itself if you allow.
I’m all about saving money myself, but the amount of Temflex I use per graft is pretty much insignificant, so I like to go with what I think is the better product.
I do wrap the grafts with 2" parafilm as well. That is much more cost (about $30 per roll) but a roll lasts a really long time.