I buy a lot of fabrics from my local op shops, not that they have a lot, some times none, but you have to get lucky sometimes! I have one favourite store which charges no more than $2.00 NZ a remnant piece, and if I am buying larger pieces they just throw in the smaller scraps. I also look for good cotton fabrics in the second hand clothing racks but not so many clothes are made from cotton these days, but I always manage to find a bargin once in a while.
Love your three fabrics, look forward to seeing what you decide upon design wise for them.
Gal