Ask HN: Advice on structuring and pricing my work

A few months ago I graduated from school and took a marketing job at a technology company. Hired primarily to build out paid media efforts, I've pretty much become the owner of all technical marketing stuffz due to previous programming experience and ongoing miscommunications with our development team.

In the process I've gained a number of marketable skills such as A/B testing, tag management, marketing automation systems, user tracking/analytics, and conversion optimization, etc. Through unsolicited referrals I've received several clients for moonlighting work. These started out small and easy enough to price, such as auditing the existing PPC accounts for local businesses, building out a few landing pages, or implementing a drip marketing system. But the jobs I've been getting recently are a lot less straightforward and require a combination of SEM consulting, business coaching, and minor development work to implement everything.

I really like where my projects have been heading lately, but I'm running into an issue pricing and structuring my services. For pure PPC work, I'd charge a flat-fee for an initial account audit or keyword research and then an ongoing percentage of spend for maintenance and optimization. With CPA targets to protect the client, this has been really successful and resulted in a realized hourly rate of ~$100. This doesn't fit for my more recent projects, so I've used that hourly rate to come up with project-based pricing with a detailed SOW.

This has killed my consulting work. Several commented on my age and experience not being in line with my rates, but existing PPC clients seeking additional work had no hesitation about the value of my work before they were aware of what it translated to per-hour. Is what I'm charging unreasonable? Is there a way to hide my hourly rate, or a title I can market my services under that can help justify it?