Does it lack manner to send a card to someone who gave you cards for gift?

I think you mean that someone gave you a box of greetings cards as a gift and you're wondering if you should use one of those cards to send to them. No, you should absolutely use one! They obviously like them if they bought them for you and they'll be pleased you're using them. Not bad taste at all.

Did you ever think they don't have the money to spare for gifts...And yes that is bad taste...When a person receives a Christmas/birthday or any other kind of card, they are being thought about and that's what counts.

No, it shows that you appreciate their gift and are using the cards.

That would be a bit tacky. Is it that much of a bother to purchase your own cards or is it more thrifty to use cards sent to you? Let the choice be your own little secret. Merry Xmas. LOL