I was considering saying, "you may be looking for X, and you may think you've found it, but as you approach it, you realise that while there may be some offerings, they often aren't truly what you actually needed, even if vaguely similar or resemblant. There may seem like there are a lot of opportunities, but as you near them, you realise it's slim pickings."
I just wanted to use an expression like "it's not free picking", like imagine going to a farm during the peak season of the harvest where you can pick as many strawberries or apples as you want because the farm is actually in abundance/excess of them.
Is there any expression that sort of conveys "it's not a banquet, it's not a free-for-all"?