They are even working on getting me the evicted tenant's security deposit, the missing JANUARY rent since the place is still empty, and covering the cost of my own manager re-listing the property.

Also, how much did the electric and plumbing fixes costs?

We abated the walls, and that added $10,000 to our costs.

These are all upfront soft costs before you break ground. $300sqft to build at least.If you have any sort of mortgage on the property you will need an attorney to handle the mountain of paperwork the bank will give you for a lien release. 10k+, also probably some nightmare terms to have to build and sell immediately and god knows what.At this point a year has passed and you have spent at least $60,000 cash, you're about to break ground on a structure that will cost you at the very least $400,000 to build, you are still 1 year away from cashing out because you have to now build a house.

I paid him the normal closing cost, a few $ grand in fees, and a slightly higher interest rate than I might could have gotten conventionally. 

They have cost my business tens of thousands of dollars and countless wasted hours of follow ups and missed opportunities.

Is there any good rules of thumb to estimating the cost of a boiler?

Paying a bit more might be justified if the pro forma income is very achievable, but $360,000 seems too high unless renovations are already complete.Factor in the costs and timeline for completing renovations for the studio and the fifth park-owned home.

Additional software estimates renovation costs and provides actionable analytics.

You have to try to estimate MTR income in your area + take into account the costs associated with MTR setup.