You are likely to get as many suggestions as posts.
My suggestion is to give these a try. They will give you an introduction to decoupling/isolating, and it may be the only $28 you need to spend. Think about weight distribution, total weight, and a mild tilt back as you could either try 4@2” under each speaker, 4@2.5”, or 2.5” in the front (the drivers are bolted to the front baffle so there is probably more weight distributed to the front), and 2” in the back, which is what I use for my 175 lb speaker/stand combo.