Dealer or after market ------ hmmmm -- I guess it depends if you're a DIY person with tools and into the fun of looking for and then installing these things or would you rather take it chill and have the dealer do it. I did all installs (except the side moulding trim which was orgnlly on the car) as after market from a wide variety of sources.
The wagon (2010 used / white) came with the black rubber side molding and stock thick rubber VW mats -- love the side trim molding and think it's a very sharp look, plus if you park in parking lots with little space btwn cars, those rubber strips give your door paint a fighting chance at being protected.
Installed F/R mud flaps (ebay) -- dig them a lot -- these were VW parts with part nos - solid and well made
Fogs (evey single component ebay) -- look sharp; not super useful tho in my opinion, they do dress the front up a bit -- not a terrible DIY, but it helps if you're somewhat electrological about wiring and a basic relay power circuit
Underseat Drawrs -- Drvr/Pssngr -- super easy install - sourced from various vendors...whoever had the best deal -- can't recall at the moment -- I have em both filled with stuff....
Dash Cubby -- A must for me; it's pretty roomy -- tricky install but not that hard once you've torn into the dash, realize there is no turning back and have some patience -- again, from whoever had a decent price.
Xenon Headlights -- there's a guy on the Vortex selling these things approx $600 -- they're pretty cool -- I installed myself and got a kit from the The Retrofit Source -- pretty much wanted high qlty components and the type of expertise they offer -- as I didn't want to mess around with junk for headlights -- Ed's Vortex housing are pretty decent -- I guess projectors, go/no-go depends how much nite drvng you do.
I also snagged very inexpensive roof rack cross bars from Amazon -- I only use them when I need to secure a load to the roof -- they are mostly no on the car.
I also experimented with a receiver hitch which I subsequently sold; cldn't justify it after using it on one camping trip -- it held a rcvr tray -- all in all, the hitch is not a bad install and can be sourced for around $120 shipped from a variety of vendors
---- take your choice --- good luck