Hey Brother, I wouldn't care that much about supplements, you must remember that food is food and cannot be replaced with supplements, as the name already tells...
I only use Glutamine and creatine, and of course multivitamins and minerals. It shouldn't pass the house of 70 bucks, all these.
If you are on a bulking up phase, you should add some 100% whey protein supplement, up on raising and right after working out. And, maybe, before bedtime.
Have not bough any supps for the last about 3-4 months. So I guess it would be $0. Need to start buying again football is over now and now we hitting the weight room hard for the rest of the year and have more time for myself. What I spent normally every month was from $70-80, in Protein, creatine, glutamine, Animal Pack (vitamins).
The most essential legal bodybuilding supplement is CREATINE if you want to get big eat a lot, try to eat about 1.5 times your bodyweight in protein every day and take creatine on a cycle. Try to split the amout of carbs every day by 3 times your bodyweight. Most of the other supplements on the market are all hype, when you go in the gym and you see someone that got thick overnight almost have him take his shirt off and show you how broken out his back is.