On our MB's, buying the bulb fromt he dealer usually means free installation. (Not with cluster bulbs...)
On Canadian models, the DRL's cause the low beams to burn out a little faster, and on both the C230 and the E300 this summer, we had sets of headlamp bulbs replaced, and the dealer did them for free on both the W202 and the W210.
Give it a try!
1998 C230 "Black Betty"