Huntington beach is a totally different place than downtown LA.
IN terms of cheap.
Its really cheap just south of downtown, like around broadway and central avenue in the 40's-60's (40th st etc.) Delicious tacquerias are everywhere around there and its a short trip up to downtown.
Also, if you are down with being a little further down,the area around imperial blvd once you get to like 80th and further is way cheap and way nice.