Be aware that you are using the services of a Professional. You did say Professional in your subject line. Not your garden variety type quilter.
Long Arm machines are an investment (much like an automobile) and there is upkeep. There is also training with lots of practice to be done.
Now, if you can find an old lady, (like the one I used to have do my quilts) who bought an old broken down long arm and began doing simple pantographs across the width of the quilt, then stopped, returned to the beginning and moved down about 6 inches and did the design again, then you might get it done for less than $100.
Professional quilting is usually beautifully done. Take a look at some of those that have been posted by members of this group. They will help you decide how you want your quilt to look. Beautiful stitching, feathers and flowers are all part of making a quilt more beautiful. And the price is not unreasonable. What is the old saying "you get what you pay for" and I bet if one of the gals on the Board did it for you, you would be thrilled. I read the other day about a member who cried when she saw how beautiful her quilt was once it was finished.
Give it a try at least once when you have a quilt you really want to sparkle. In the meantime, you can try to do that stitching on your table model at home!
June