For each added connection, you introduce additional signal loss, as long as the initial signal is ok then you shouldn't need to do anything extra, but if it's a bit marginal then you might add the need for a basic masthead amp or something similar.
Given the length of time the job can potentially take, $300ish sounds pretty reasonable.
I'd certainly report their poor service to the freeview people though. Odds are they've got that much work on at the moment that they just don't think they need to care too much.



