@Elliot Grochal - I'm in Forest Hills, Queens and have also looked at small multis in the area. There are a few 3, maybe 4 unit (each unit 2/1 or so) newer buildings here. Newer - as in not pre-war.
They are priced around $1.4-1.9m, close to trains and all things, great schools, etc. - so, fantastic location. If you live in one unit and rent out the other 2-3 units @ 2000/each, you will still have to lay out your own portion each month to cover just the mortgage.
On the other hand, perhaps a more reasonable choice might be to buy a 2 family house and live on one floor and rent out the other floor. Less cost to get in, for sure. But make sure it's legal w/permits and all.
Since you will live in one of the units, part of your decision will be based on where you want to live, right? As you know, there are significant differences (numerically and desirability) between what's available in Forest Hills/Ridgewood/LIC/Douglaston/Williamsburg/Greenpoint/Bay Ridge vs. East New York/even Canarsie, etc.
Best of luck and please let us know how your search goes!