It's possible to do heirloom machine quilting on a regular domestic machine. Harriet Hargrave, Diane Gaudynski, Maureen Noble, and Sharon Schamberg and many other quilters have won prestigious awards without a longarm.
If the bulk gets too much to handle, there are ways to do a quilt in sections so that the sectioning does not show. Marti Michell has a book on this now, but I first saw the method explained in detail in a book by another quilter (whose name escapes me at the moment; she hasn't published in awhile) who won best of show at Paducah several years in a row.
For myself, I found it much easier on my body to machine quilt on my domestic machine standing up. (Much easier on the shoulders!) Building a large work surface that is flush with the bed of the sewing machine helps a lot too.