Structure Commercial Lease Option

[Mohegan]

I have a commercial property for sale or lease which i have received an offer for, however we would like to structure this in our best interest... Any good ideas please throw em my way..
I have the property listed as: 19500 sq ft facility - warehouse zoned mfg. with 4k sq ft office space. Available for purchase 1.5 Million w/ 5 acres...or for lease for 6.25 per sq ft - Triple Net . This is a good price for this area since the facility is like new and has excellent location and last city sewer till next city. .. anyways, we received an offer ..
offer A: to lease 6.00 sq ft. NNN Terms 3 yrs. with two 5 yr options. with deposit of one month. It will be used for Mfg/ Distribution. However the wish to do improvements to suit their needs.. The scope of work for new facade is estimate at approx. 80 K -
offer b: is for Lessor (us ) to do rennovations for 5.00 sq ft , (this one i didnt like no way )

offer A & B: during lease, Option to purchase property for the amount of 1,400,000 with credit to seller( lessor) for the cost of improvments as indicated in Offer A: and 10 % of all rent paid credited towards purchase price.

We still want our asking price of 1.5 million and 6.25 per sq ft. ( we feel its worth this seeing that building this would be much more & that no more building permits will be issued to this area for one year )  We will also consider partial or complete owner financing. We do not want to loose this potential buyer but would like to receive our asking price and appreciation and possible holding costs.
How should we counter this offer to be appealing , but in our best interest? Throw any lease structe ideas my way
Thanks all !!!