That three pack from Quad is probably our stuff, so you should just buckle down and buy it.
OK, better answer: There are a variety of soft top cleaners out there, and a few general purpose cleaners you can use. Get a product that specifically says it's OK for vinyl. Vinyl is a chemically "soft" product, and harsh chemicals can damage it. You can use Simple Green on your soft top as well.
And, you can use mild soap and water, and a scrub brush. This works very well.
WINDOWS: You need to be even more careful what type of chemicals you put on clear vinyl windows. I'd stick to a product made specifically for vinyl "glass", or stick to soap, water and soft cotton cloth.