You can probably find another investor to do this.2 - Establish contractors credit at all of your suppliers, with 30-60 day no interest (suppliers like giving incentives at the start). 

I have not purchased through Rent to Retirement, HOWEVER I did purchase a supposedly "turnkey" property from one of their Kansas City suppliers.

It's the entire property not just business, so some future value.According to one of the suppliers they project about 60k gallons a month, though apparently margins (if I'm reading the rack rates right) currently in the area are only about 15 cents/gallon, which is nothing if it's a $1.2mil property that also needs $200-300k on top for pumps (tanks are from 2015 but dispensers have been removed), inventory, and startup costs.

All the suppliers have lost their dang minds.

I already found suppliers who can do this.

He said his gas supplier makes him use their credit card processing service for everything in the store or they can't sell their gas and they charge higher than normal processing fees.

The pros of ordering your own (finish) materials are you will save some money (maybe, depending on your supplier list and what types of discounts they offer you) and likely have a lot more flexibility to choose what you want, as opposed to getting a few options presented by a GC.

This is a range from the cheapest materials to the most high end materials available in store.Vinyl Plank Flooring: $1.79 - $15.00 per sq ftHardwood: $4.49+ per sq ftTile: $0.70 - $28.17 per tilePaint: $19.98 - $79.98 per gallonDoors: $51.46 - $199.00Windows: $377 - $880Cabinets: $59 - $309 eachRefrigerators: $598 - $2,998Stoves: $548 - $1,938Dishwashers: $348 - $804Microwaves: $238 - $498Single Bathroom Vanity: $139 - $499Toilets: $99 - $379Water Heaters: $429 - $1,500If you have purchased materials from other local suppliers in store (not custom ordered), please drop their info and pricing below.

In our business new builds our lumber suppliers deliver all ours so we never go shopping for lumber anymore anyway. 

If you are planning on buying and/or renovating preowned homes, there will be many ideas about what you can do and what consumers want to buy.There will also be 90+ suppliers there offering everything from customer financing programs, to community design services, to all the materials and tools you need to complete any task related to manufactured homes.