I think Repeat is very important, even for the one item, one sale store.
Why? Because 9 times out of 10 if that same person is willing to come back he is more prone to refer others to me as well. Not to mention that if the one Item owner ever did decide to add another item for sale or even an upgrade for that matter. the repeat visitor could be his catalyst into the new revenue scopes.
In my eyes, a quality user is a BUYER (Whether they are paying for a product or a service), thus the focus on Conversions. If the traffic isn't converting, its just traffic. Free tactics to attract potential buyers is old news & depending on what the fee product / service is, will reflect how easy it's going to be to add an upgrade charge for a full version or full access.
I think the majority of one item sales out there with no intention on ever expanding or adding more products is stagnated in thought already (A one hit wonder like Vanilla Ice & the Candy man to the music business).... A little off topic (yet complimenting in a analogical sense), I met the CandyMan in person in Las Vegas back in 1997 after his late 80's early 90's hit ("Knockin' Boots" a duet he did with Tone Loc).... The funny part is that he was working as a Telemarketer for "NOS Communications"... NOS Communications in "97" solicited the famous "Change your phone service calls & save".
From Top chart Hit to telemarketing Solicitation...... I hear he is still trying to make a comeback though
anyways, My opinion is that Repeat business is good business if you plan on staying in business & expanding in the future.