There are some longarms that are less costly than others...there are also some places that handle used equipment and they're usually okay as well. I have a Gammill for the same reason you posted...it cost way more than I wanted to pay, but it eases my work load so much it's worth it!
Another option you may look into is having someone else longarm your quilts for you. There are several on the Board who do it and do a heckuva good job!
Whatever you do, don't give up!