We have used Knak.io for landing page templates and Perkuto's "Allegro" for email in the past and both work great. Can defo recommend. I think Knak still give you 1 template for free too which is nice to play around with, and it imports it directly into Marketo for you.
Take a look and let me know what you think.
Thanks for the recommendation David.
Jessica, as David mentions, we do self-service Marketo emails and landing pages through knak.io
Our agency (Revenue Pulse) also specializes in the creation of custom email and landing page templates. It is more expensive but you can get pixel-perfect exactly what you want and our team has tons of experience in B2B lead generation optimization.