So far, Mike at
OE Discount Parts has been excellent! Just placed my first order. Free ground UPS with $50+ orders, but you must select it in checkout.
He found the MB equivalent part numbers for all my items, and they were all at least a little bit cheaper, to much lower cost on a few.
Sign up for an account there, then send him messages through their system under the My Account link. They e-mail you when a response is posted (maybe in a day or two if he's busy).
9/26/09 Update: Mike found all the OEM parts including the washer tank, packed them well, and shipped them fast by free UPS Ground! Highly recommended.