Are you looking for tops to practice on? I agree that charity groups in your area would probably love to have a longarmer volunteer to quilt some of their quilts. You might ask for $5 or so for the thread you will use, per quilt, unless you want that to be your donation to the charity.
If you are looking to buy tops for yourself, I piece tops for sale. You can pm me if that is what you need.
Good luck with your new machine!