Go to your local quilt shop and see what they have in the way of machines that were traded in. Sometimes they have an older machine (better than the new ones) that you can get at a good price
Go to yard/garage sales, rummage sales, look in the local ads in your newspaper, tell friends to keep their eyes open for you, look on CraigsList for your area, look on EBay. I got a wonderful FW and a Singer Red Eye (1914 vintage) both in perfect working order on EBay and very reasonable.
If there is a quilt guild near you, put the word in there also. Maybe one of the members has a machine they don't use anymore.
DON'T GIVE UP QUILTING! Do some hand quilting til you can get a machine.
DEAR GOD IN HEAVEN, please bless this wonderful quilter and bring a machine to her doorstep somehow, some way.
Amen.