I use an old footlocker that my grandpa used to have when he was in the Army. It was free and I was able to customize it for not a lot of money. I'm not sure how much Army footlockers cost, though. :/
I got mine from Canadian tire for only 100$ and they usually go on sale for 85$
Top jock tack boxes are beautiful but they are pricey because they are fully custom and hand made
I've also heard about Alfako which are really good!
Stephex, Cheval Liberté or la Gee are the ones that I know which are the biggest and the most adapted :)