Block heater for 420sel

[benzboy87]

Anyone know of a good aftermarket block heater for a 420sel? The dealer wants $70 for one and I think that is way too much. I have seen some on ebay for around $45 (advertised for diesels but is the basically universal for mercedes) but can't tell what brand they are - picture's too small and my eyes aren't what they used to be! Any help would be greatly appreciated.