Use a finishing nailer and a lap siding gun.  

We paid about $1095 for a 4ton 13seer, but there were extra costs in the new line set ($225) & the new Evap coil ($350).Install labor for us runs around $600 to qualify for the 'contractor installed warranty'.

Is the A/C coil exposed and the line set not hooked up?

As I had the same intentions to wholesale.I had a meeting with the President of my brokerage ,Champion Realty, Jon Coile, and They concluded that because of the potential liability of being sued by Sellers not understanding the transaction no matter the disclosures later after the closing, the lack of coverage from their E&O insurance on these transaction, and the lack of money staying within the company as those transactions count as personal transaction, they do no support or allow their agents to perform any assignment type investments. 

(House is vacant and I'm in option period) Bank will budge a bit on price, but not enough to cover the whole repair, Its a unit from 2005ish so I'm guessing I'll have to redo the entire system (coils on the inside, lines, etc) with the new non-freon alternative.

I"m having someone come out to clean the ducts and AC coil but don't know what to do if this doesn't take care of the problem. 

We had someone come look and when they replaced the unit the sellers did not match our coil inside with the unit outside so our unit is pushing half a ton more air than the coil can handle.

Especially since the new a/c requires a new evap coil, line set etc.

A/C issues are typically due to neglect like failing to clean the coils or change the air filter.

They found out a failure in the coil had caused a failure in the condenser so they replaced the coil.