I have not used them so take this with a grain of salt.
I first used the plastic LEGO blocks.
Then I cut up a rubber door mat in to 4 squares that could sit under the feet (not a glove like fit - they just sat on top).
Then someone in the forums made mention that in the unlikely event the trailer gets hit by lightning, itís best to have the metal feet in direct contact with the ground.
It made sense to me so I donít use anything for that purpose now
Having said that - if youíre looking for something like the product you linked - a $15 rubber welcome mat cut to 4 square may serve the purpose at a steep discount over the product referenced. It will not be a custom fit but once the stabilizer pad is on the rubber square - the square isnít moving anywhere.
Last - this product references a fit to an Equalizer Stabilizer Pad - not sure thatís what comes on an Airstream - I think theyíre BAL stabilizers? I could be wrong....
Hope this is even marginally helpful