Whey protein isolate (I use isolation from n2bm.com) 60g after each workout with 50g oatmeal
Creatine (I use ancient strength from n2bm.com) 5g before each workout
Greens powder (I use cytoforme by novapharma) 1 scoop before bed
Psyllium husk (I order it bulk off truenutrition.com. Code tkz564 will save you 5% on the entire website) 10g before bed
Digestive enzymes with each meal (I buy them at costco)
6g fish oil (I am using krill from n2bm.com) per day + 3g cla per day + 3g evening primrose oil per day
1 serving of probiotics each morning before breakfast.
1 serving of a multivitamin each day (I use ruthless 3d from n2bm.com)
1 serving of calcium magnesium with vitamin d pre and post workout (I buy it at costco)
1 serving of BCAA pre and post workout ( I use gear from n2bm.com)
Most of those aren't essential per say, but still beneficial. If money is tight the best supplements to take are calcium magnesium with vitamin d, fish oil and psyllium husk.