One way to control expense variables is to pay for labor only, and supply materials that you pay for.

I think in the more economically challenged blue collar areas, many families literally do not have enough money to afford proper cleaning supplies.

Usually they didn't have sufficient instruction about what needed to be done and most days, they didn't have the supplies they needed to work, so little or nothing got done.

You may eventually get to a point where you've worked with particular buyers enough and supplied them with enough solid deals they may start buying from you sight-unseen...but you should always allow them their opportunity to inspect the property.Most cases the only parties involved will be the "motivated seller", you and your buyer.

Mind if I ask which part of the supply chain you work on?

I think a maintenance schedule is a great idea as long as you are not trying to generate more income from the tenant, and you supply the filter to the tenant because it is your property.Joe Gore

The cheap supply of houses in my area is quickly dwindling.

I'm not at the point where I think purchasing a truck/van to haul supplies (-ie, lumber, cabinets, water heaters, etc) is justified.  

If you are playing in the major cities, it's not a great cashflow market, instead, it is more of a market timing market where you buy, hang on for dear life and then sell.On bigger deals, you'll find mostly pension funds, insurance companies and large REITs competing for a short supply of assets and driving down cap rates.In smaller cities/areas, it acts like many other US markets.Overall, very high barriers to entry, but you can see appreciation that other markets can only dream about.

I supply salt and shovels... for major blizzards I pay for removal or offer a discount on rent for them to handle it on their own.