Rents do go up over time (as do costs, but hopefully at a lower rate). 

Just a way to reduce the cost of us having a place there.

I doubt switching to a different property at 5% down will leave cash flow negative as well but you’ll lose closing costs on both ends from your equity.Selling before 5 years is typically a net negative unless you are flipping.

I want to convert the church into a house, which will cost about 100k.

There is a prohibition against posting the landlord's names if they are found to be in violation of the ordinance.The ordinance includes a $1 million mitigation fund for landlords to offset the costs associated with accepting vouchers.

If so what is your cost to build per sq. ft.?

I would think having a landlord or rental dwelling policy is a much higher cost to be mindful of.

In addition, get GRANULAR on which expenses/costs are tenant responsibility vs which stay with you.

Without knowing the area really well it is hard to know how much of that is the cost of land baked in.

If not I'd just put a new one in and eat the cost.