Multiply that by the number of years left on existing roof.

A general tool is Gross Rent Multiplier (GRM), not very precise but handy when doing a quick value assessment.

Find the total monthly rent and multiply it by 0.50 to find average expenses per month.  

Multiply current payments to the new payments and see if it will be worth it.

That % can then be multiplied by your annual utilities, security system, mortgage payment, insurance, and property taxes as expenses that can be charged to the business.There are some neuances that have to be observed when doing this so check with your tax professional. 2008 is the first business year that I am going to charge these expeneses after hearing about it from my tax professional early last year.

If I multiply that by 12 I get $3,000 in cash flow per year.

Last 3 columns shows how the CoC varies as % rent varies.Here's the equation if you want it:NOI - Mortgage / DP = 15%[50%*(PP * % Rent * 12) - (75%*PP * $5.37/$1,000 * 12)] / 25%*PP = 15%This reduces to:[6 * PP * % Rent - .04833 * PP] / 25% * PP = 15%PP cancels out, multiply the top by 4 (or divide by 25%) gives you24 * % Rent - .19332 = 15%Move the constant and divide by 24 gives% Rent = (.15 + .19332) / 24 = .34332/24 = .014332 = 1.43%Given a 25% down payment (ignoring closing costs and reno), if rents are 1.43% of purchase price, you achieve a 15% cash on cash return assuming the 50% expense rule.

If the past is prologue, by funding a Homeowners Refinance Act, similar to the one used during the Great Depression, we could multiply the effectiveness of the current Bailout Plan.

The appraiser would adjust according for the monthly rental amount based on features, amenties, condition, location, and proximity to determine market rent and apply the most resonable GRM to your gross monthly rent.So for instance if your market gross rents are determined to be $3000 (750 per unit X 4) and the GRM was 75X then your 3000 would be multiplied by 75 to end up with a market value of $$225,000.Cap rates are great but no residential appraiser uses CAP rate, you can however use it for your "own," analysis to determine your ROI criteria but it has no bearing till you enter 5+ multi family, commercial, retail, and business financing. 

I can't help but imagine what buying power $200-$300K would give me to multiply my portfolio.