Again, I'm not local so I'm just taking every cost and push-back on progress at face value.It's $80 per door, per year, plus the one time inspection fee, which I was thinking was $180, but don't recall exactly right now. 

There is a significant upfront cost associated with this but I have calculated it will average 2.2 years per building to save the cost I’m currently paying for oil.

my goal is to keep it as simple and low cost as possible.   

I always tell buyers DO NOT BUY if you're not ready, but if you are ready, waiting can cost you. 

That gives me additional income and offsets the risk of loss if I have a longer vacancy once they leave. 25% sounds like a lot, but consider what it will cost them to find another rental in the next 30 days that will allow a three-month lease, plus the cost of moving, setting up utilities, etc.There's nothing wrong with trying to help out a good tenant, but don't hurt yourself in the process.

Hopefully they accept the increase because it sounds like it will cost you thousands to turn it over for a new tenant.

It's a cost of doing business.

If your operating costs are below the market, your NOI will likely be matched closer to the appraisal's market rents.

A lender may want all properties insured by the same company with the same renewal date, so you may need to adjust things and see your agent before applying for a blanket mortgage simply to know what the costs will be. 

There are closing cost so either you will need to pay all those or have some downpayment to cover them otherwise the seller is paying to offload it.