I know what you mean. I have all that in my current gym, but I see few with such a good setup. Along with it being less than a 5 minute walk from my house, it makes me reluctant to relocate.
That said, back in work soon and dreading the 6pm rush in there with only 3 squat racks. Usually fine on a Friday. A pain on a Monday though.
I am going back to just whey and a multi vitamin supplement I think. Have tried a few others, but just wasting money.
There really isn't much that's worth buying:
High strength vitamin D3 because it's likely you're not getting enough sun
Creatine - works in it's 1-2%-y way, worth taking for vegetarians/vegans (as mentioned earlier in thread)
Caffeine - who needs to pay £ for pre-workouts when this is all that's effective about them and you can just drink coffee (not that nasty instant stuff though...)
Good quality Omega 3 oil if you don't eat much oily fish or get it in your diet via some other means (I have a bit of seafood but buy the Nordic Oil lemon flavoured liquid off Amazon)
Multi-vitamins are decent insurance on a diet when food is more limited but the sports type '3 a day!' ones are a waste of money
If you're female and avoid red meat and dairy, iron and zinc
Other stuff that works is grey area where you can buy online easily although it's not really of benefit to training directly; things like yohimbine for stubborn fat loss (not that many people get lean enough to start targeting stubborn areas), melatonin for sleep, then obviously anything that actually helps for gainz is on the really naughty list.
I actually buy a 70% casein, 30% whey blend now. I tend to make proats, protein fluff/desert far more than I drink a shake and the mix (MyProtein Milk Protein Smooth) handles heat better and is theoretically a better choice for a last meal since it's digested slower.