I use Wallypark almost exclusively, but my company pays for it. They are not cheap. Currently they are 17.95/day but they offer a AAA discount, that is pretty good when you stay four or five days. Their shuttle service is outstanding.
I noticed last night as I was returning to Wallypark the The Parking Spot is offering covered self park now for 79.95/per week. Additional days are pro-rated.
Don't forget that all the parking places just outside of LAX add a 10% city tax.