I tried looking for grappling mats online and they are really pricey, ranging from ~150 to $600 or more. Or for puzzle mats, each square is about $35 and the two sites I went to (one was fighters warehouse) had a minimum order I could not meet.

This is for home use for my two boys, ages 6 & 8, who are beginning Brazilian jiu-jitsu students. I'm thinking something around 10'x 10'. Something we can take out onto the living room when needed and practice various techniques including takedowns. 

Where can I find affordable grappling mats? Or are there other cheap alternatives? I was hoping to stay under $100. Is that even possible?

btw I tried craigslist by searching: "grappling mats" and "sparring mats". No dice though.