Back on topic here...let me ask you a question...if $$ is a factor, then why did you buy a 4runner and not a Kia Sorento?? Ok, i admit, that's an extreme example.
As far as GX vs. 4runner, there are good reasons why people pay the extra $$ for the GX...like luxury things (Mark levinson, memory seats, sound insulation, wood stuff, etc.), superb customer service, and extra warranty period.
As for the X5, it has an independent suspension and unibody...both of which are more costly to develop than solid axle and body-on-frame. That's just one part. BMW is a luxury brandname and has similar benefits to the Lexus benefits.
With the X5, FX, Porsche, you're not comparing the same class of vehicle since these are cross-overs, not true rough-&-tough SUVs.
For you, you did not want all the extra pampering stuff...so you chose the 4runner. Others want it.