I heard one of the jacks stores was selling their old display tanks/racks... wanna say it was like $200 for a 4 tank rack... not sure if they still have any though... think I saw it on cincy reef, may be worth looking at... as they would all be ready to be plumbed, if not already.
Most small tanks dont come "reef ready" but we could pump out some holes, easily, club has hole saws for premium membs aswell...
The trap should still work, though them being attracted to food would increase the chances of you catching them... the food does not catch them, just entices them to enter... I would imagine that over the course of the day some fish may be curious enough to find them selfs in it without the use of food.
Unfortunately with Ich it's a time game... I would advise supplementing garlic into his diet, and look into QT'ing him for the time being, even if it is something as simple as a rubber maid tote, heater, and air stone... less than $30 bucks would get him in a QT today with those components, and allow you time to get something more permanent setup.
You can fore go the bio wheel filter so long as you do atleast a 20% water change every day till you get a filter or get the more permanent setup together.