I just use a very basic dechlorinator. Mine doesn't even take out heavy metals. Once I run out, I'll probably switch to Prime as well as I've heard lots of good things about it. If I'm not mistaken, Prime is made by Seachem.
I wouldn't worry about adding too many supplements. It seems like a lot of aquarium products are there for the manufacturers to make more money. If you know what you are doing, you can cut out a lot of unnecessary products and save yourself money. For example, the Marineland filter cartridges they recommend you change every 4 to 6 weeks or whatever? I haven't used them in my filters in about 5 years. Activated carbon? I have it on hand in case I need it, but I don't regularly run it in any of my filters.