here's another option too
$100 for a pair
As for are they safe, there's varying opinions on them.
I've got 1 weekend run on mine plus some trailering, alittle over 300 miles so far. My jeep is only a 4 cyl. but I do have 35 x 16 x 15 boggers on the axle with the adapters. After the first day, I wheeled like I would have without them and so far so good. Mine are 2 piece which most consider even worse than the one piece ones. I bought mine from the website above which was the cheapest I could find.