Ok, I'll chime in on the first picture posted by CoupeGirl since it used to be my car and I've sat there and taken it apart first hand.

Total price for my install from stock to that picture was $900. That included everything (labor, paint, and install). Paint was $200 since it had to be custom matched and theres some metal flake in there as well. Install for a shop like I went to for a typcial Double-DIN is around $250 but was included in mine so honestly expect to pay $200 on top of this piece and paint unless you do it yourself. My installer did say that his guy had a tough time with it. Total time from drop off to pick up was about a week (hours to do it, I have no clue)

Here's some key things that you NEED to know before once you gut everything out. Frist, you're going to need to have the Double-DIN unit there as a template. Secondly, we're actually quite lucky that once you cut away the original bottom of the Single-DIN bracket the Double-DIN fits in nicely, tight, but it works. You'll have to prop it up with something (some small pieces of sub box wood), you won't see it so it really won't matter. In turn you'll more than likely lose your change holder (useless anyway). Thirdly, if you plan on selling your car but want to keep the Double-DIN unit you'll have to buy a new OEM front console @ ~$130

Can it be done a mass scale? Maybe but it won't be cheap. I let a shop do it because if something went wrong they would be liable for it. Even when taking out the unit for servicing. Once you start cutting the OEM piece and filling it with Bondo or Resin the integrity of the piece diminishes. The stock plastic is pretty sturdy.

Good luck with it, if it does turn out to be reasonable I might do it again. If this does come to fruition but you don't want to install it yourself, you might want to go custom all the way since it'll end up being about $300 - $350 to install due to the removal and cutting of internal pieces.