I made a mistake, there is a $5k config with high memory bandwidth. The Max chip has two tiers (I incorrectly thought the tiers were based on memory capacity), you need the higher tier Max GPU upgrade (+$300) to get the 614 GB/s memory bandwidth but you don't need to upgrade the RAM to 128 GB to get the full memory bandwidth. So to get the 614 GB/s you need to upgrade to the max chip + upgraded GPU, but you can spec it at only 48gb if you want. So the total for an m5 max with 614 GB/s memory bandwidth is $4999-$9999 depending on config.

Still 3x lower memory Bandwidth than a dual 3090 setup which you can build for $3k with parts from facebook marketplace and run in your basement.