Irvine CA

Unless you go to public campgrounds and move every couple of weeks, it's not going to be cheap.
You might want to look into Huntington by the sea in Huntington Beach 800 439-3466. It won't be the closest, but probably the most reasonable. Kind of.

Only thing I know is close to Disneyland.

http://www.goodsamcamping.com/travel/campgroundsandrvparks/searchresults.aspx?city=Orange&state=CA

Newport dunes is way expensive.

Maybe here but a bit of a commute with traffic.
http://www.canyonrvpark.com/park.map/

The Orange County Fairgrounds has camping,but during events you have to leave.

Probably not a long term solution but San Onofre State Beach and San Mateo Campground have camping (no hookups). Nothing in Orange Co. will be cheap though.
http://www.reserveamerica.com/camping/san-onofre-sb/r/campgroundDetails.do?contractCode=CA&parkId=120085#sr

you're going to have a hard time finding anything near Irvine for that long.
especially for the time you want to be there. state park campgrounds in the area, are probably already reserved for those times.
we reserved some coastal sites for February and couldn't even get 5 days in a row anywhere.

i'd suggest a mobilehome park, for that length of time.
or you can go inland and probably find something. like Lake Elsinore.

Thanks for all the responses they miror my thoughts

How about checking the County Parks in Orange County.