That is sort of my thinking since I am looking at a car with no warranty. I have no problem paying a couple thousand dollars to correct a problem but the posts I have read suggest it is a far more costly fix than that. May as well buy a car with known engine failure issues.
The only problem is the air suspension is tied to all those other excellent Ultra options, cooled seats, massage and adjustible rear seats, rear a/c etc.
The Arnott and Strutmaster conversions seem to be for the 400 only. Memoryfab makes a complete replacement air system that will fit the 430 http://www.memoryfab.com/products/detail_suspension_48/ for $2300 without labour.
Tanabe and Tein make coilover systems for the 430 for under $1500.00 but I can't tell if this completely replaces the air ride. http://www.autocarparts.com/c_lexus_LS_430_c_Suspension/
JICMAGIC wants almost $2400.00 http://www.hopupracing.com/jicmaflviplu3.html
I would assume you can disable the air ride and just go over to the coilovers since they would be kind of like what is on the non air 430 models.
EDIT: Parts.com has the rear air struts for $755.00 http://www.parts.com/lexus/2005-lexus-ls-4...nsion-parts.cfm I am not sure what the single most common component failure with the air systems is but if that is the worst of it, not so bad.