^ This. I have some of these too and they are fantastic. Not cheap, but the separation is very noticeable in all the A/B'ing I have done. Even if you go the DIY route and just make some cheap wood stands, adding these on top will help. I'd pick them over those isopads that Auralex make any day.
If you're looking for proper stands, depending on your mixing space you could look into making some really quality stands with PVC piping with leadshot in them. Or, buy some
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All really depends on how serious you're getting with the acoustics. It does matter how the room sounds and money will have to be spent to make it the best it can be but you can be frugal and get it done if you look into making these things yourself.