What is an reasonable conversion ratio for SaaS startup? Using bottom up approach

This is two conversion rates - you want the tl;dr response - figure 5% each. It really depends on what you are offering, how competitive it is, and what you price it at. Know this though, you can really work on improving conversion rates and you always should work to improve them. You should do this during the early stages of launch with a small group of users, get some user flow, then work on conversions, PMF, etc., and dial it all up BEFORE you switch to banging the drum really hard to get tons of visitors.

The first metric is a function of "did I attract the right people to my site, is this really my target audience(s), and is my value prop 10x strong enough for them to try it". Find out how you can get people from kicking the tires to trying it for free in the shortest time - like say "in 5 minutes after your next meeting you can be holding the transcript, etc."

Once they try it you want to push via email to get them to engage, to send out the results from the first meeting to everyone, etc. Don't go for the throat, go for the repeated use and once this becomes a drug they will pull the trigger - it's actually affordable - in fact, your first pay tier should be 19.95 anyway and the second one bump up to 29.95 (your call..it just seems to cheap to me). I would make sure that when you send them the results you hammer them to forward the results to everyone in the meeting, they will all have a group ah-ha moment and there will be group approval that will serve as internal social proof that they should jump on board. Make sure you give them a written list of cool uses for your output to let them see the full value it holds - "now that you have the results you can do x and y and z etc."

get early conversion numbers, benchmark, tune, measure, improve then go after the traffic once the hiccups are out of the messaging, features, and onboarding.