Did you build a machine with 4x 3090 ? I looking for a way to build such a machine for ML training.
BTW, depending on where you're at in your ML journey, Jeremy Howard from FastAI says you should focus more on using hosted instances like paperspace until you really need to get your own machine. Unless, of course, you enjoy linux sysadmin tasks. :) It can get really annoying trying to match the right version of CUDA with the version of Pytorch you're trying to get running for the newest model you're trying.
Total, without GPUs and their power supplies: $2900