Vacancy? 

Mortgage would be about $3,300 and I think I could get at least $1,600 for each unit ($4,800 in gross rents - I would live in one unit) leaving me with a cashflow of $1,500 a month (before I set aside money for maintenance, possible property management, vacancy). 

thanksturns out i only added town tax and not city tax asloI also added in 5% for cap ex and 5% for vacancy 5% for repairs and maintenance.cash flow is now quite low, however in the next calculation, I lowered the offer price to 57k which makes it a bit better, is 12% cash on cash a good investment in your eyes?

Insurance paid by HOA.135 hoa, 68 management.68 vacancies, 68 for repairs. 680 rent,19146135 686868-------576-680104 cash flow3540  per year cash flow if I pay cash. 7% ROIIf mortgage- 40k @4%, with a down payment of 10kROR on 10k in the form of principal for first year is 6.4% increasing about a percent each year for the duration of the 30 year loan. adding a 1% for the $100 cash flow.would this be ok to get my feet wet?

That will save you $180/month. 10% Vacancy seems really high.

I calculate that with $250 per month allocated towards repairs and CapEx, $100 per month for vacancy, the $590 per month in utilities insurance and taxes, and about $160 for a mortgage payment ($25,600 at 6%), I would still cash flow almost $300 per month.

Vacancy is more expensive in landlording, and going after deadbeats is usually a fool's errand..

I was busy with other business at the last vacancy, had a huge flood of early interest (a lot of them that were seemingly qualified), these people were persistent, had great income and credit, so I signed them up and took the listings down.  

Don't forget that you are likely to have a period of higher vacancy as you increase rent and turn over the tenant base.

And if it is make it less desirable if there are no porches or any car garage ( I know hoe disturbing it can be in the winter there without a garage.BTW it is going to be a cash deal and after all the expenses (property tax, maintenance, vacancy, management, cap ex) it comes out to about 10% cash on cash, assuming fully rented for $650 each unit.Also another question I had is how long after purchasing a house in cash can I refinance ?