Have you tried Sticky Tac to stop the dancing? A friend does that and the machine sits firm......

You can get the rubbery stuff on a roll (is it sold as shelf liner or keyboard pad or something) from the store (hardware store, grocery store, drug store) and cut off a length and double it and place under your machine (works well under foot pedals too), or you can buy a Janome Muffling Mat, or other mat and that will help keep any machine in place. I have to say I have several machines, and none of them dance on a nice solid surface. Even my 13 pound Janome stays in place. The most solidity is from older solid metal machines like my vintage Pfaffs though. But treat yourself to a nice sewing table like an Arrow table or other made-for-sewing cabinet. Notice how low or high you would like that table or cabinet as well, so that it fits you when you sit and sew. Have a nice time shopping for your new machine and your new room...take your time. :)

It's not your machine - it's the table it's on! If you put your machine on a more solid surface, perhaps closer to a leg, it won't move around.

Put a towel on the table and put the machine on top. works for me

I sew at my dining table and my machine would "dance" when I positioned it on the end of 90" table. I moved it to the long side of the table (closer to the leg) and the dancing stopped!

This. Any machine will bounce on certain surfaces. I double the shelf liner and get no bounce or other movement. Also, when on a recent retreat, I discovered the closer I moved the machine to the table legs, the less bounce (these were foldable plastic tables).