I like the 90/10 rule. If 90 percent of what you do is locked on, the other 10 can cram it with walnuts. This applies to supplements thusly: good food, good rest and good training take you to 90% while supplements can help take you the next 10%. To paraphrase Tenacious D, they give you a little more juice, help you take 'er to the limit.
What I'm getting at is, evaluate your wants and needs for supplements. Biotest makes good ones that I like alot. When I can afford supplements, Biotest's are the ones I use. When I have to choose between buying 10 pounds of beef and dozens of eggs or buying an order of supplements, I choose the wholesome vittles.
Now, if you have all kinds of expendable income, this may be moot for you. If having everything locked on and going to the next 10% is something you want and can do, have at it. Grow! is good stuff and if I could afford it I would put Alpha Male and Carbolin 19 in my pez dispenser. One serving of Alpha Male and one cap of Carbolin 19 in the morning is my all time favorite effective/economical stack.
Another litle nugget I've gleaned from buying supplements with my "magic bullet" mentality: A little for a long time is better then alot all at once. I have a tendency to spend my money and use the maximum dosage of a product and wind up not spending enough to use it for a significant amount of time. I now am old enough and secure/patient/mature(?) enough to realize the value of using a more moderate amount of [insert any supplement here] and giving it some time to do it's thing. Gently persuade the body, don't try to pharmacologically manhandle it.
Hope that helps and good luck,