You can switch to https for Marketo-hosted landing pages, like Grant said.
I did a professional services contract to do this back in March of this year and the cost was $1,200. If you're dependent upon Marketo for consulting throughout the process, this is a fine price. If you're largely technically independent and just hand off the certificates and private keys to Marketo professional services, some might consider this very expensive for very few hours of work. But there's no way around it, because engineering needs to be involved no matter what.
Getting the certificate set up is not difficult, same process as if you were going to do so without Marketo at all.
The largest chunk of time investment in making this happen is switching all existing references from "http://" to "https://"—all images, JS, CSS, and other external references called within a secure landing page need to switch these over or you'll have trouble with compatibility. If you've had Marketo for only a few months, not a big deal. If you have lots of landing pages and references and assets, this can be a huge and tedious to-do list. It's also one of those things where if you aren't proactive, you won't get automated emails telling you something is wrong, you'll just have prospects who have a mediocre or undesirable experience and you won't hear about it. You'll have to do an internal audit of all your internal assets and get a list of all changes that need to happen, then switch them over.
(Or, if you were writing code with "//" instead of "https://" or "http://", you'll have an easier time with this!)
Cheers,
Edward Unthank | Founder, Etumos
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