I don't necessarily think the friend was trying to take advantage of her. I don't charge friends or family for cakes(though I do not have a business yet, so maybe my point of view is different). If I couldn't afford to make one, I would tell them at the time they asked how much I would need to cover costs, or what I would need for them to buy. We live paycheck to paycheck too so they would have to understand that.
My aunt made my wedding cake for free, she had to take two days off work to finish it, she even took classes to perfect her skills for it. While of course not everyone can afford to be that generous, I would hope she would have been able to tell me when I asked if she could do the cake, how much money she would need for it. If after the wedding she had said, "oh by the way, I need $300 for the cake", of course I would have been upset.
As someone who has recently lost loved ones, I understand what jscakes is saying...that cake isn't worth a damaged friendship. I didn't realize that it was a best friend, you should be able to tell your best friend anything, including that you can't afford to give her a cake for free. People can't read your mind, I am guilty of not being direct either, and then get upset when I don't get what I want. But its not fair to the person that I get upset because they didn't offer.
The night before my father passed, I really wanted to go see my parents. I hadn't seen my parents for almost two weeks, because of being busy with christmas shopping and whatnot, and missed them. I hinted around I wanted to go (I don't drive) but because I didn't want to bother my husband and was afraid he would get irritated, I never come out and asked and thought, "well I will see them tomorrow". That night my father died in his sleep of a cardiac arrest.
After, part of me was mad at my husband, because I thought, "well if you had offered to take me, then I would have saw him one last time." He would have taken me if I had asked. Obviously he didn't know I wanted to go, and it wasn't his fault. Deep down it was actually myself I was mad at.
Its really worth speaking up.