Try to find a wrecked Crossfire or SLK at a local junkyard; post in the parts wanted classified section of this forum; check with a MB dealer (will be cheaper than a Chrysler dealer).

Alternatively, you could measure the dimensions and try to match it with a net from another make/model, e.g., BMW, VW, etc... Since the part is a netted bungee cord, a close match should stretch into place.

http://www.ebay.com/itm/HONDA-S2000-MAP-POCKET-CARGO-NET-WITH-CLIPS-/181133086214?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a2c5f8e06&vxp=mtr