Consider This: Suitsupply Sevilla Blue Plain Suit, $399
If you only have one suit, make it a navy one. Suitsupply is known for balancing European taste and quality with affordability, and clocking in at around $400, this notch-lapel suit is perfect for just about any occasion short of a black tie gathering. The jacket is canvassed—meaning there's a layer of cotton and horsehair that'll allow it to mold to your body over time. It's a great first suit that's actually worth keeping around long after you've gotten the dough to get something next level.