Dell has the Dell USB-C Power Adapter Plus – 45W for $28.49.
http://www.dell.com/en-us/member/…ccessories
I believe most places have tax.
I wanted this to go with my Dell XPS 13 just so I have 1 less AC adapter to plug in to go with my Nexus 6P and Pixel C. It’s pretty cheap and you know it’s a genuine item. It seems buying them elsewhere, even Amazon, is kind of a crapshoot for genuine charges.
It also comes with an extra USB port on the charger so you can charge something else with the 1 outlet.