I look at it this way. I can use my walking foot and a 'wavy' stitch and produce some pretty nice looking results on my DSM. I am "getting there" with some half decent meandering on my DSM on kid-sized quilts. For those larger or special quilts, well, you can get a lot of professional quilting done for what it would cost for your own long arm setup.
Oh, and someone mentioned renting time on a machine. That is another option if you really yearn to DIY. And you can certainly rent a lot of time for what it would cost to buy your own.