Do I just stop accepting hand me downs for my son?

I have a 3 year old son. My Sister in law and husband's friend are both rich and both have son's who are 2 years older than my son, so they have given me SO many clothes, I really have no need to buy any. Sometimes I will buy him some shoes or clothes if they are cute, but I have so many clothes and some never even worn with the tags on. I am blessed, but my Mother in law and grandmother in law both mention every time my son is around them, they will say "I will buy you some new clothes or shoes so you don't have to wear them old hand me downs" in a pitiful voice like we are poor and never buy our son clothes. I mean I don't buy him stuff like my SIL because I haven't needed to because of her and my husbands friend. I have 49 pairs of pants, 200 shirts, 44 pairs of shorts, 15 coats, 20 jackets, 100+ pairs of socks, 30 pairs of shoes, dozens of jammies, over 100 sweaters and long sleeve shirts, so why would I buy? They are all gap and name brand and barely used. Am I a bad mom for not buying my son his own clothes? I feel like **** because of what they said. I feel like I am trash. Why do they give it to me if they don't want him wearing it?