What would you get? 400 is a flexible amount say +/- 15%
Seiko Presage or some kind of Tissot Powermatic (on sale or off Joma).
Laco!
Pre owned certina, seiko, or citizen.
a Citizen Tsuyosa propably
Get a used seiko on eBay and $360 of rigatoni (preferably new, not used).
Orient star has a bunch of great watches around that price point. I really like the Orient Star Classic because of its classic 38mm case size and interesting power reserve complication.
Seiko Speedtimer.
Browse AliExpress, you’re gonna get much better fit, finish and regulation compared to mass produced brands like Seiko. It’s also gonna be easier to avoid pressed, hollow bracelets and mineral glass, since even a €60 watch on AliExpress will have solid end links, milled clasp, AR sapphire, screw down crown, 200m WR and proper finishing. Here’s a €250 watch for example:
Seiko Turtle SRPE93 has been next on my list for a while. Grey market price hovers about $375 USD.
Casio lineage for quarts titanium radio and solar?
Used Seiko Laurel inspired alpinist, such as the SPB243 and its ilk. Wonderful GADA watch.
citizen tsuyosa, orient kamasu