Your repairs budget is possibly low, but could be somewhat accurate depending on the rehab.  

It was a bit of a unicorn as his budget was just barely enough to get into an entry-level home. 

The best thing is to perform preventive maintenance and have a log on the unit itself, install CO2 and water sensors that can be monitored with an app like a video camera and budget for replacement one thing at a time.

House is in the construction phase at the moment with a 40K construction budget.

In your rehab budget are you paying yourself?

You want to be equal or better then the competition and be able to stay within budget. 

Perhaps the inspection can reveal your biggest contingencies and associated costs and you can budget for them in your counteroffer.Mike

The time stated to finalize this deal suggests to me the buyer has had time to get further educated but still if the numbers really make since to you maybe you have made a great deal.If you can implement tight controls and your contractor is reliable to bring the project in on time and within budget then things should turn out good for you.

I have a certain amount of money in the personal budget that is being set aside for our real estate ventures.

Assuming you put down 25% at 4% interest, your debt service will be almost $1,000/month, not including taxes, insurance, utilities, maintenance, repairs, capex budgeting and vacancies.