This will sound crazy but you may want to get an unlisted 800 number. If you are web based only you probably won’t have very many people calling the 800 directory.
With no listing it will force them to your site plus you won’t get erronous calls from the directory. You will be surprised how many wrong numbers you receive, and pay for…
My personal view about vanity numbers is they take more time to dial than a normal number because I have to look at the phone each time to figure out the number/letter to push. But ….there probably is an app for that /;-)