04 LS430 UL rear air conditiong fliter, WTF
 

Oh come on, I need the rear air condition air filter (88508-50080) and its almost $100!!!!!!!.

Anybody know where I can get this cheaper?

$28.79 USD at http://www.rockauto.com/en/moreinfo.php?pk=1524324, BECK/ARNLEY part # 0422109

I dont think ive ever replaced my rear AC filter. Is there a warning that comes on like with the front AC unit?

Don't think so, but you can go into the NAV maintenance section and select and name a warning as Rear AC Filter and input when you want to be warned based on mileage and/or date.

inspect what's there and perhaps you can get away with just blowing the dirt out. Or buy a non OEM filter, which is what I did and it's been totally fine for the last 2 yrs

The rear AC filter actually lasts many times as long as the cabin filter. That's because the cabin filter must filter dirty air taken in from the outside. The rear filter is not subjected to that, as it draws it's air in from the interior of the car and not from the outside. The cabin filter has already taken out the bulk of debris before it get's to the rear. It is actually hard to tell when the rear filter needs to be replaced just by looking at it. I changed mine at 60,000 miles and it didn't look like it needed it!