This is a question that more likely could be asked, "What would be a reasonable asking price for my residential income units"? If this were indeed the question my answer would be:
Determine what the remaining income is after deducting all your annual operating expenses from all of your collected annual income.
Divide this figure by 8%. Check your result and then divide by 6.
The first result should give you a good asking price. The second division will show you how much you are asking per unit.
You could then check on LoopNet to see what others in the Long Beach area are asking for their listings for similar properties and similar locations. For a modest sum you can also utilize the service from LoopNet that will provide you with comparable sales for your area in the past. A word of caution though: when looking at comparable sales, accept only sales within the last 12 months as a measurement.
I hope this helps a bit. However, my best advice is find a good commercial listing agent for residential income units. Personally, I would avoid giving a listing to an agency that sales mostly single-family homes. While these agencies are excellent in their field, very often they are not as good when it comes to commercial transactions. There are many fine commercial property brokerages that will be more than happy to help you.
Rob Baird, CA RE License #544165, (One of the oldest active licenses in CA)
Jul 1, 2010