Why were you buying Intex filters twice a month? Most cartridge filters can simply be rinsed off and they should last you a number of years. Also, cartridge filters can be the most energy efficient filters to use for a pool so I would not discount them.

For AG pools, your best value may be a combo pack but unfortunately, to get a large filter, which you want, you have to go with a large pump, which you really don't want.

The two combos I would consider are the following:

Pentair Sand Combo

Pentair Cartridge Combo

You can get better combinations purchasing the pump and filter separately but it will cost a lot more money.