OK...here we go...rims, spacers & lug bolts oh my
Good luck finding 4 AMG's in decent shape for $600. $600 each & you'll be fine. Check e-bay you might get lucky.
First thing to do is decide on what size rim (height & width) you want. Staggered or all the same? I'm guessing you'll want 17" or 18 " rims w/ 8-8.5" front - 8-9.5" rear
Figure out a tire size that will work best for the rims.
Then understand what range of offsets will fit the SL in that rim size.
Lots of info here on all that...+ you need to READ,READ & READ some more.
Then the best part....LUG BOLTS!! Don't get me started on lug bolts
Again....READ, READ, READ & READ some more!!
Ask questions as you go & you'll figure it out