All I ask for is your Support

My sister-in-law is being very helpful when it comes to wedding suggestions. She brings me favors from other people's weddings, pictures of their dresses, a website to a photographer who she thought was cool, and several other things. Recently she told me of the idea of having a smaller version of the cake you want and then having a sheet cake served to guest as a way to cut cost. I told her that I had heard about that and a few other ideas I'd been thinking about. One was having a fake cake, with a real piece for the cutting and the rest would be Styrofoam or whatever, and everyone would be served sheet cake. My Eldest sister called me "a red necked hill billie" while her husband told me that idea was "cheap". Be that as it may, I think they could have expressed their feelings in a different manor. Then my B-i-L says to me, "You only get married once. Have a REAL cake." To which I responded, "Yes, but I don't want to be paying for it for the rest of my life either." They just don't seem to get it, F and I do not have a lot of money. I have some serious credit card debt that is holding me back, and I don't know, a MORTGAGE. They seem to think the money is free flowing. I feel that every time I bring up something about the wedding, they gang up on me, telling me I'm being "cheap".
Is it so much to ask that my family support me? Seriously, is it? I don't want my memories of my family's involvement of my wedding to be a bad one, and so far, that's all I've got.