What's your LP-12 on? The sidewalk?

I have a new (to me) LP-12 (pretty loaded -- Lingo, Ekos, T-Kable, etc) sitting on a very solid wood table. I'm willing to go to something more serious, and I wonder what you recommend? I am in a basement with cement walls, so wall mounted racks are not an option.

Here's an idea I have, and maybe someone who knows more about this stuff than I can help. I have, in my garage, a piece of concrete that probably came from a sidewalk repair. It's a hunk of stuff that's about 2 feet by 3 feet by about six inches. I'm thinking that if I could get something appropriate under it so that it were at a decent height and completely level, that it would be very inert. It's gotta weigh 150 pounds. But is inert the way to go with a Linn suspension? Maybe the concrete with something tech-y on the top?

I really can't justify the $1500 for a used Arcici, and while the Rix Rax look great, they too are waaay out of the question.

Thoughts? Help!

Appreciation hereby given in advance for all feedback.

Put in on some leveled cement building blocks (the type that are used in the construction of basements).
The best stand for an LP12 is the Sound Organisation TT stand that was originally made for the Linn LP12. It is very low cost, and was only about $150 when they were new. I don't know if SO still makes them or not. The LP12 should be on a low height, lightweight, rigid stand. This gives the best results for interfacing with the internal suspension of the table. When I used to sell the Linn tables, we always sold a SO stand with it. It sounds good.
Float that piece of concrete in a huge sandbox supported by some heavy timbers.
mana acoustics - they are *the best* stands for an lp12. the difference is not subtle at all. they're expensive, but incredible.