If you spend a lot of money on someone, it puts them in a bad position, like other people said. They feel obligated to spend to return the favor, and if they don't have the money to spare on a similarly expensive gift, then they just feel bad. Even if you don't demand that they buy you something expensive, they still feel like they should reciprocate in order to be a decent human being.
Basically, money can't buy friends. It's just not how it works, and in the off-chance that they don't feel bad about not returning the favor, then they're not worth being friends with. I'd reccomend MAKING your own gifts for them; it doesn't cost as much to you, it doesn't make them feel obligated to pay a lot of money, and showing that you care by spending the time on something like a card or a piece of artwork or a handcrafted item.
That's what I'm planning on doing for my friends, at least.
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