Funding repairs, supplies and CapEx expenses

[Dan Mann]

I'm running numbers through a spreadsheet to try to establish cash flow.

Is there a preferred method of establishing a cost for supplies, CapEx and repair expenses?
Do you use a fixed amount or percentage of rental income or just an estimate?

I realize the condition of the property has a bearing, but where I run into problems on a percentage base is lower rents. Somewhere here I've picked up a random figure I don't want to go below for CapEx, but figuring 10% of rent sometimes places this figure below this random figure. For example I'd like a minimum of $100 going into CapEx, but if rent is $800 then I'm at $80 for SFR.

As I write this it seems silly in that I'm concerned about $20, if it is that tight of an estimate I think I'd be in trouble. But, if I have several categories where I'm off it can start to influence the decision to purchase or not.

I’m taking the advice here on BP to run a couple properties each day to see if they cash flow to get a better understanding of my market.

Am I being overly analytical?