@Sean Ade First welcome back to the Raleigh area and congrats on the success in your duplex.
As far as your question, If you are looking for "outter City limits" you do not have enough to get a 6-10 unit. Your 150k at 25% down (commercial standard) you are looking at 600k. You wont find find anything that cheap in the near areas of Raleigh. Places like Zebulon, Wendell, Clayton, Garner, Fuquay are all past those price points for 6+ units. And are prolly the most up and coming areas. Those would also be considered Raleigh suburbs. If you look farther out you might find deals in your sweet spot. I would look at places like Alamance county (Burlington, Mebane, Graham), Greensboro, Angier, and Lillington. These places are growing with Raleigh but at variring clips. I would take a look at them and see what best fits your goals. You have a leg up being from here or having family here.
Another note, I know Portland is seeing a lot of growth as well. You are able to get your gains tax free from it being your primary residence for the at least two years. That rule is actually written as 2 out of the last 5 years. So you may have the ability to hold it for up to 3 more years and still not pay tax on gains up to 250k, or 500k if you are married. So that could also be a play if it fits your goals.
Hope it helps and there are a handful of meetups in the area so reach out once you move back and I can let you know when and where they will be.
Best,