Regarding competition, Hourville probably does something similar.
Have you searched through Craigslist to find listings of independent instructors? If you are in search for a personal instructor, where would you look? I think you would Google with specific terms "independent italian tutor" or something like that. Try those phrases and see what comes up. I am sure if you spend enough time on Google, you'll at least identify a few people to talk to.
The next step is to just cold call them. This is very difficult for most people to do, but is the easiest way to get in touch with your potential customers. Though cold call has a negative connotation associated (none of us want to receive unsolicited phone calls), if you are nice about it, it does produce results. Be honest with them and let them know that you are asking for their feedback. Once they figure out you are not pushing a product on to them, people are surprisingly nice at times (from personal experience of cold calling).
My main point is, you need to talk to as many customers (independent instructors) as possible, and as early on as possible. Incorporating early feedback is the best way to make sure you are building something that your customers will actually find beneficial.
So get the phones going. It's hard and time consuming, but is the best way to get quality information that will save you a lot of trouble in the future. If you can't do this during regular weekday hours, see if weekends will work. Since these are independent instructors, I presume they will take your call during a Saturday morning as well.