No, that's not right. If you want to avoid paying ridiculous commissions, use Vanguard as the brokerage (i.e., open an account at Vanguard) and buy the shares there.
(There are other places that let you buy Vanguard funds without a commission, but your current brokerages apparently isn't one of them so going with Vanguard directly is the simplest advice.)
Another option would be to buy VOO, the ETF equivalent of VFINX, at your current broker (or using Robinhood). That might have lower overall costs even after the $7.95 equity trade fee because the expense ratio is lower. It depends how often and how many shares at a time you plan to buy vs. how long it would take you to build up the $10,000 balance to convert VFINX to VFIAX.