@Stryker Brown
Ask him for a Rent Roll and P&L.
Ask him do these represent normal operations going forward?
Review his expenses - do they make sense? If the Expense factor is below 30%, likely there's something missing. For smaller parks the expense ratio usually are higher (40%+)
Review his income - was the monthly income stream consistent? Did they factor in collections loss or vacancy?
Based your offer price on his current NOI (with your adjustments) divided by the market cap rate.
During the due diligence period, if you get it under contract, you'll have to try and confirm as many of the P&L assumptions as you can. If you find evidence (ie utilities were way higher than stated), you let the seller know what you found and see what explanation he gives. If there are enough issues, then you'll likely have to ask for a retrade on price.
RE Cap Ex: Ask yourself - if I put in a $100K in cap ex, what value will I get from that? it's like remodeling a kitchen before you sell a home. If it costs $50K to remodel and it only adds $40K of value, then likely you won't do it. If the cap ex exceeds the value created, then you'll need to get some of that cap ex discounted from the price.
Instead of valuing the empty lots, think about what the exit price will look like and if you're going to offer more than the current value, ask yourself how much of the value add am I willing to pay for upfront?
The empty lots or 'undermarket rents' - that represents your value add that you earn for doing the work to drive the NOI. In a competitive bidding situation, you might have to pay more to win the deal. Just keep in mind the more you pay, the lower your return. Know what your walk away number is.
Also keep in mind that buyers set pricing, not sellers. If no one's willing to pay his $400K price then eventually, he'll have to come off that number
(note: I've been involved in deals where the seller is valuing the park based on the 'redevelopment' potential and not as an MHP - if there's a developer that's willing to pay, then they'll outbid me every time)
While buyers set pricing, though, sellers set timing! It may be awhile before the sellers are willing to accept what the true market value is.
That's where it pays to continually follow up.