You can use your own funds, use a HELOC or do a cash out refinance to cover the costs.

Cost per lead (CPL) is crucial—it shows how much you're paying to get a potential seller or buyer’s info, and you want this as low as possible without sacrificing quality.

What are the costs for the value adds, the expected hold time, and the expected sale price? 

Larger properties offer economies of scale and better financing terms, but they also come with more complexities and higher upfront costs.

Not knowing the configuration of the church the appraisal may be less than your purchase cost plus rehab costs.  

Also, what are some other low cost amenities that I can add to my STR that will yield a higher ROI?

For me as well as the seller.First, you have to define Sub to financing.Do you mean the reckless kind where you overpay for a property, take over the financing and borrow from others to cover closing costs and holding costs when you have no money, no credit, no income, no reserves and can't tell a warranty deed from a deed of trust and you close on the kitchen counteror do you meanbuying below market value, already having a nice income, having reserves, using escrow and title, already understanding the due on sale clause, have done a lot of creative purchases and know when to use and when not to use creative finance and how to recover if something goes amiss?

Credit cards have the same limitation on the amount you can borrow and will likely end up costing more than private lenders.

Replacing one bad fixture between material and labor can end up being 3X the cost of buying the better quality fixture in the first place.  

I wasn’t prepared to lose so much of my savings as carrying cost basically I paid for the tenants to live there for 3 months + my own living expenses in that time.