Low budget? Plano/Doskocil can be had in a padlock style for
cheap. Personally I like the Plano Airglide---not as much foam contact.
Up a step are the Plano Pro cases, such as the 108420.
Then you get to Pelican and Hardigg cases---but they are not low budget.
If you keep a gun in a foam lined case, toss in a few dessicant packs.
ANY moisture in the case translates into foam patterned rust eventually.