Patio Door Replacement

It shouldn't be too hard, since the opening is already there.   You just need to fill in a couple of feet with wall or windows and put in one or two new door jambs (depending on where you want the new door, centered with windows or walls on either side, or on one side with a wall or window on the other side).  Leave your old lintel in place unless you insist on a taller door, in which case you are looking for more work.

I don't know what you call expensive.  French doors cost more than regular ones, but the lumber required and the rest of the materials shouldn't cost too much.

I wouldn't consider it a big deal for me to do, but I don't know what kinds of tools and experience you have.  It would be an all day job for me to tear out the old door, frame in the new opening, install the new door and drywall the left over two feet (after installing the exterior siding and insulating).  I would want an assistant, but it would not be an absolute necessity.  Plaster work and painting will of course add time to the project beyond the one day it takes to install the door.

I am begining to like profitbob, great advise. The home improvement centers sell french doors to fit in arcadia door openings (1 1/2 ") shorter than standard door openings about $700 last I checked                  C7

I have a 6 ft.  paito door I would like to replace with a dog door in the paito door.  It would be a small dog door.  Can you take a glass pain out of a french door and replace it with a dog door   What company would do this? 

I don't know of any company that does this, but a local handyman should be able to do the job.  The panes are designed to be replaced, so it will come out easy enough.  Then it's just a matter of making the right-sized panel for the opening and putting two hinges at the top and weather stripping around the edges (or over lapping the edge of the dog door).