@karim - where in socal are you looking? For LA, It's tough to find mf that cash flows in B or better neighborhoods, roughly speaking west of downtown and North of the 10. I've found cash flowing properties (but barely) in East LA (Boyle Heights, city terrace and east LA) - and more so in South LA - communities such as Vernon and Huntington Park. Those that cash flow decently will have quite a bit of deferred maintenance, or have some other big issue(s). Other than parts of Boyle heights, I have not looked into these areas very closely since they're not my cup of tea.
A few people I've talked to find luck in the central Valley, deep in the ie, and desert communities.
Another option is to buy a single family in a B neighborhood in the low threes and try to get $1600 to 2k for it - not super great but gets you in the game at a relatively low price point. Plus you don't need to deal with rent control.
You can also try to find mf properties that don't cash flow at all, which would then command a low ask price. You then pay the relocation, make a few upgrades, and get the rents to market+. This is especially true in LA because of rent control, and works better in hot markets. What I like about this strategy is that you can achieve high rents without having to manage a ton of properties, which generally mean less maintenence, capex and headache.
Also especially in hot markets that are rent controlled, and you're dealing with below market rent units, I don't really figure in vacancy. Vacancy is exactly what I want and wish for. Because as soon as a unit becomes vacant, a buyer's willingness to pay goes up, since it gives them the opportunity to charge market rents or house hack.