Importance of Good Speaker Stands?

Stands can make a significant difference, but it will depend upon how resolving both your speakers and the system is, as well as how discriminating you are as to just how much difference it will make, and how much that is worth to you. One warning I'd give you - those vibrapods tend to leave marks on everything you put on them, especially wood and metal. Those marks are nearly impossible to remove. I learned this the hard way. Cheapest fill material is play sand from your local mega-hardware store that has "mom&pop", who used to own the local hardware store down the street, working for minimum wage as greeters. The sand itself is dirt cheap...no I mean it. Better make sure it doesn't come from China and off-gas some rancid cat-piss smell that melts the tip of your cartridge off. Wait a minute, that's kitty litter filler I'm thinking of. You could probably get some of that Chinese drywall for free and fill your stands with it, but I'd just use the sand. Seriously, filling them can deaden the metallic ringing resonances that may exist and will create a more solid foundation for your speakers with less room to flex. We're talking at levels that we can't exactly measure, but yes, you could potentially hear it. The only way to really find out is to try, which may amount only to a bit of a hassle and sand on your living room floor. If it doesn't work out you've got some nice drainage for a garden bed.

It's late, what can I say. I was very serious about the Vibrapods though.

I would try the fill like Jax2 suggested. With those particular speakers, I would look at your situation from a strict resonance control perspective. So true about the mom&pop example. The cat-piss issue can be rectified by LRTIGB (little round things in glass bottles). They equally work well as stink absorbers as well as quantOnium poopy eliminators.

I have Liedtke stainless steel "Diva Exclusive" stands and have filled them with very fine quartz sand (odorless :-)) from the DIY store. As pointed out by Jax2 and Vandermeulen: dirt cheap and may prove to be a tremendously effective tweak. One word of warning, so you don't have to find out the hard way: don't fill the stands to the rim, it'll kill the sound, 2/3 to 3/4 of their height will probably give you the best results (at least that is what worked best for me).

Jax' warning about vibrapods leaving a residue is accurate. It's also true of other vibration-absorbing pads like the rubber and cork pads. After one bad experience I've always used a layer of plastic wrap on each side of the vibration pad. I have not tested different brands or weights of plastic wrap for their sonic attributes.

Instead of the Vibrapods try Herbie's big fat black dots between the stand and your speakers. Very economical with a generous trial period. As already suggested try filling the stands. How much to fill them and with what is the experimental part. I've had good experiences with a combination of kitty litter and fine lead shot (#8 I think). If I get to a point where I need to fill stands again, I would try the micro bearing fill sold by Star Sound Technologies.

http://herbiesaudiolab.home.att.net/spkrfeet.htm#cone