I actually just went through a round of magnetizing my painted guys.
There's multiple ways you can go about magnetizing. My first try I used washers and magnetic strips. It worked but theres a few drawbacks.
The second way I did it was paint magnetic paint onto my movement trays & then cut magnetic strips to fit into the bases. Its takes a couple layers of paint, but it works. I used a craft magnet that comes in a long strip. Its easily cuttable with a blade. For the BfSP goblins, nearly all stay when I turn them upside down. For the Dark Elves a few fall if turned upside down. So I assume were I to use this method on the Sauras it would work even less. The thing is though, they dont need to be suspended in the air, just be able to stay stable on an incline or in transit.
Then there's the rare earth magnet route. This one is the most serious & works the best. Its also the most expensive. You can score some on the internet or even at hobby stores. For metal sheets I've been pointed to this: http://www.litkoaero.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=LAI&Product_Code=GSM001fs
I can't personally say anything about them, nor do I know another source. Hope this helps.