How can I politely tell my cousins to stop lecturing me every time I buy something for myself or my kids?

Every time I buy something that is not a necesity for myself or my kids, I get lectured by my cousins. I bought my daughter an $80 dvd player for our long car rides, and I got lectured, I purchased a 2 new nightstands for my bedroom, lecture. I am a very responsible person financially, we have over $10,000 in the bank, and we add to our savings anywhere from $200-$400 a month. The rest, we spend because we barely have any bills. Anyways, I posted on my facebook status that I was really excited that we were going to buy a pool for the summer, and I recieved 3 responses. One of my cousins wrote "please tell me it's an above ground pool", her sister (my other cousin) wrote: "Please tell me it's a plastic one.." and her smart *** boyfriend wrote "If you're goingt to get a pool you might as well get a jacuzzi too." Wtf???? I don't want to sound like a *****, but I think they're just jealous because my cousins used to get everything they wanted from their mom before she passed away, and now their dad doesn't give them any spending money and the only money they have is settlement money from their law suits, and her boyfriend doesn't make much and has to support his mom and brother. I'm not saying that their situations aren't sad, but it doesn't make it okay for them to treat me this way. Please, how can I respond to make them understand what they're doing without sounding like a *****? Thank you.