Part numbers for the various kits are in this document: - note the page titles, make sure you're looking at the proper numbers for Gen1 or Gen2, and also note some items are different for sedan / wagon / coupe:

http://www.w124performance.com/images/W124_AMG_kits/124_AMG_body_kits.pdf

You want the 'B6-' numbers, which are complete kits. Lowest price I know of is from here, enter the number without the B (i.e., type in 6-602-0730, not B6-602-0730 (dashes not required). Warning... their shipping is expensive, 15% flate rate, which eats up most of the savings. Call your local dealer and see if they'll cut you a deal, then you can pick it up locally and skip the steep S&H fees.