Yes it could be a wheel bearing and no, the job is not overly complicated. It does take some tools, and on your car I believe once you get to the wheel bearings you might as well change the rotors as they are integral with the bearing outer housing. Not too costly, check the "buy parts" tab in the logo for this site above, and search for some more explicit instructions.

I would do both sides especially if you elect to change the rotors, and then I would also do the brake pads. Remember, the key to success with bearings is maintaining cleanliness. Dirt in the grease or any grit inside the housing is unhealthy for bearings.

Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)