I took the same course as OP. You're making a lot of assumptions here. I have to chime in, because 30x500 is almost the exact opposite of what you've described.
1. We spent an overwhelming amount of time learning how to find, identify, and dissect pains and problems. Importantly, all of this was done well before we spent any time about thinking what types of products we should sell.
(Side note: Check out this free lesson from 30x500 to get an idea of how we approach "pains"... http://unicornfree.com/wp-content/uploads/2011/10/Lesson-12-...)
2. The problem with OP wasn't that she wasn't "expert enough" to solve the problem SaaS Compass addresses. (There's no question that her product benefits SaaS owners.) It was a matter of her perceived authority, and that's something that can - and, knowing Jaana, will - be established over time. (e.g. through content marketing, publishing helpful, free information on her blog, etc.)
"I'd encourage anyone looking to sell a product like this to spend just as much time, if not more, becoming an expert on said field before selling advice."
3. "Expert" is a very broad term, so this is wishy-washy advice. At what point is someone considered an expert? Can I teach 3 year olds to play soccer even if I'm not an expert soccer player? Hmmm, I think we're on to something. On top of that, what type of expert does one need to be? "Said field" is equally vague. Fields are BIG. You don't need to be an all-round SaaS expert to sell to SaaS owners. You just need to be an expert at one particular slice of SaaS, and know more about that than most SaaS owners do. (For instance, you can be a CRO expert and sell CRO advice that's targeted and tailored to SaaS owners and their CRO problems.)