Mmmm.. Gaff tape my favorite thing in the world.
I order in 10 roll bulk from the theatre supply places in town and have it shipped to my office. It's about 200 for a ten pack.
Rentapro definitely sells these (Lee, not Rosco, and no swatches to be had sadly) - that's why I was there in the first place. However, not hugely flash friendly, as the minimum purchase is something like 2' x 4' (think it was about $120 too so not really cheap either). I have a lot of CTO and the window green now!
I use Rentapro (A LOT), I also got some chinese language catalogs from the lobby of the school of performing arts in wanchai and just called number and ordered. A really good resource for info on equipment are the people at the fringe club- they do like 5 productions a week and are always willing to let you know who their suppliers are.
rentapro sounds like it's worth checking out.
thanks again everyone