the roof needs a complete overhaul due to sagging, sinking, and the shingles have no more asphalt on them to protect against the weather. 

Pound the pavement!

In the interest of future ownership and financing, new asphalt will be placed this spring.

We’re also capable of performing concrete and asphalt work in-house.

Are you looking at asphalt shingles? 

Why not get a contract with the owners of the strip center, build in your due diligence period and work in a contingency that you will only purchase if you are able to negotiate sale of the land with the present land owner... then pound the pavement and sit down with the owner of the land, see if you could strike a deal or an option to purchase at a set point from today - 10 years, or whatever time frame you build in.  

You can drive around looking for vacant homes thats free, I could keep goin on and on..Save your money dudeThink about investing that money into yourself first....be eager and hungry, dont give in and put those feet to the pavement..It will all start to fall in place.

Definitely a fixer upper, like $25/foot for interior, exterior, landscaping, asphalt improvement.

Is if direct mailing or networking and hitting the pavement, but which pavement and how do I know they are "tired or retiring soon or plan to retire"

When you go to sell it the potential buyer(s) will almost for sure have a home inspection done and then they will probably want you to replace the roof so you might as well do it now. 15 years is along time for a roof (assuming that it is asphalt composition).