Cheapest way to get to Westminster from Downtown LA?

I'd like some suggestions on how to cheaply get from Downtown LA (around the Financial District, Union station...area) to Westminster in OC, CA (specifically the Little Saigon Market area there) cheaply. I hope to be able to leave early in the morning (between 6:00am - 8:30am) and return at around noon on the same day.

I have considered taking an Uber, which will cost me between $42 and $55 and will take me roughly 1hr, but would like some alternatives. I haven't really found any good bus routes yet, and as far as I'm aware the LA metro does not go sufficiently far from downtown LA to be able to get near Westminster to make it worthwhile to book a short car trip afterwards there (e.g. I don't think it goes as far as Garden Grove, which if it did would allow me to then take a short car trip to Westminster).

EDIT: This is a three person round trip, so it would help if the total cost of transporting all three people is considered.