I'm pretty sure they would have let us demo what you had, unless it was 100+ years old.

I would demo the surround, pull the window, install glass block with window insert, install backer and retile.

That's myself, my parents, father-in-law and subcontractors I used for the roof and doing some demo work inside.  

For demo work you could hire unskilled workers, and only need a minimally qualified supervisor to make sure they keep moving.If you do decide to the full job, or want to investigate the possibility further, get The book on Flipping Houses by J.

It is in south San Francisco, the code officer told me that this house has the thickest binder in city history.It turned out that an old garage was demoed by the Fannie Mae upon city demand.

I've paid between $6k and $12k for comparably sized demos.

Need to deduct from that the cost of demo and debris removal for a buildable lot.

Since Friday we've completed demo work, replaced a floor joist, and removed an ugly and useless wall (other than being load-bearing, that is) to open the floor plan.

One suggestion -- buy some tools to break down the demo debris a little better.

For these reasons I would get some quotes and tell the seller this is the best you found and that the garage has to be demoed before closing or no deal.