You want the net income after all expenses like, maintenance, utilities, taxes, insurance, property management (if needed), if the property is vacant figure that in, and Cap Expenditures (any big ticket items that might need fixing or replacing once you own), things like the A/C unit, water heater etc.

I have noticed some potential low cost rental properties in my area for purchase.

The real reason was long-term low interest rates.

If they stay low a long time and you take the money you save and use it to pay down the principal, you may have made an excellent choice.My opinion is most people are better off with fixed rate loans.

 $42,000 is not all that bad, I see some comps where other investors are buying from providers I have never heard of in the mid 50's ' low 60's.  

Or did I do the right thing by lowing my offer due to the work it needed.

So, my numbers look like this:$1,580/month income$400 "lease" payment to Owner$80 Lawn/Snow$60 Trash Pickup$90 Water/Sewer$125 Electric$125 Propane for Hot Water$150 Maintenance $250 Property Tax$50 InsuranceShould leave a net cash flow as-is of $250/month.

Agents are usually not investors, so they just think investors make low ball offers. 

I agree with the previous poster: The sooner you can move up into >5 units, the better....UNLESS you want to use FHA/Fannie/Freddie financing (low down payment), or unless you want to live in one of the units.

I bought The Book on Investing In Real Estate with No (and Low) Money Down and am working my way through it.