You can sometimes pick up an old upholstery machine for a few hundred dollars that is up to the task. Just be sure it has a 'walking foot'. I have an old Singer that will stitch about anything that you can fit under the foot and a Thompson 'mini-walker' that is not as robust but will do a credible job. It is well worth the cost to have the ability to build your own interior and a fun skill to learn.
Mark
