Isolation platform for the power amps

For that price, I would recommend as thick a piece of granite as you can afford used in a 1" deep sand filled box. Forget air suspensions.

DIY is the lowest cost option by far, and depending on how handy you are, and how much effort you want to put into it you can come up with a very attractive and effective stand with minimal cost. I made some using butcher blocks from TJ Max ($20 each for the block). Depending on what kind of footer you put on it they'll cost less than $30 each, and probably no more assembly time than $100+ stands. You can use other material for the platform too, such as a simple MDF, granite, etc. I made another pair using flagstone from Home Depot (2" x 18" x 18"). Talk about cheap, but they are heavy, very effective, and IMHO pretty attractive.

If you make your own isolation platforms I would suggest putting them on brass audio points of some type.

i have my amps sitting on brass cones then 2" maple, isoblocks between that and another platform then cones to the floor. complete isolation and it sounds that way too.