Supplements suck that way, sorry. I've found a couple brands that work for me (Nature's Way, Horbäach), but I'm no supplement expert. I'd try to find a mid-price option that didn't seem too sketchy.

As for nootropic stacks and whatnot: never heard of them, although they seem interesting. I personally take 2g of tyrosine along with vitamin D and a vitamin B complex (plus a couple medical rx). I would start at 500mg-1g, and add more after a week if you felt you needed to. I have taken tyrosine with omega 3s but never regularly; I didn't notice an interaction at the time.