Need help finding a formal dress for an upcoming event

I’ve been invited to a semi-formal evening event (kind of like a mix between a wedding and a corporate dinner) and I’m completely lost when it comes to finding the right formal dress. I don’t usually dress up much, so I’m feeling a bit overwhelmed 😅 I’ve been browsing online and most of what I see is either way too expensive or just not my style. I was hoping to find something elegant but modern—nothing too flashy, but still special enough for the occasion. I came across this site and was actually kind of surprised by the variety. Some of the dresses look pretty chic and not too over-the-top. Has anyone ordered from them before? How’s the fit and quality? Also open to any other recommendations—bonus points if they ship to Australia! I need something ASAP, so any help would be really appreciated.