I just Googled and you have a PetSmart in Grande Prairie. I'd go there and buy a couple 55-gallon tanks. Split the fish between the tanks. I don't like Cupramine, but since the disease is to progressed, it's probably your best bet (assuming you don't have Chloroquine phosphate as a treatment option). From your description, I would be concerned that both the TT and the hypo treatments (particularly hypo) would take too long.

However, you could try starting TT and if the fish all continue to eat, they should be ok. If that's the case, buy 3 40-gallon tanks. Your Tangs are pretty small, so you should be ok with a smaller tank doing the TT method because you're changing the water. This way you have the fish split between two tanks, and one dry/bleached.

You should buy a SeaChem Ammonia Alert for each tank (don't let it ever dry out), and some Prime or AmQuel. API test kits are compatible with ammonia detoxifiers, Salifert is not. Ammonia is more likely to kill your fish in a QT than the Ich.

In the future, with your fish list, I would strongly recommend a good-sized UV Sterilizer. Aqua UV is a good brand.

Thank you everyone for all the good advice. I decided to go buy a 50 gallon tank from pet smart and put some cupramine in it. All the fish are in there minus the clowns (RIP) and will continue to be in there for 10 weeks. Keeping my fingers crossed.