I hate hearing about a kid getting into their parent's gun stash... it never ends well. If you are going to have firearms, it is your responsibility to keep them secure.
Without kids this might be as easy as sticking it in a drawer but they can still be stolen. If you have loved ones that need to be saved from themselves, there are many options out there: safes, gun lockers, trigger locks, even hideaway cabinets.
For security with quick access nothing beats a quick safe. These come in many forms, small shelf models, beefier stand-up models, hideaways, drawer vaults, just Google "quick access safes" and you will see what is available. Most are small safes with quick key codes or even a fingerprint scanners for fast access. They aren’t serious fortresses, but they keep honest people honest and are small enough to be hidden. You can secure it to a shelf, under a bed, etc. Your gun can be safely nearby, loaded and ready if ever needed. GunVault, Sentry and Stack-On make pretty good options and run about $100 or so for base models.
Real gun vaults are awesome for serious security and fire protection but these can easily run in the thousands of dollars and are extremely heavy. They range in size, some are huge with massive interior real estate for pistols, rifles, ammo, etc. I have one that is considered small but still weighs 400 pounds. You can find smaller 12-14 gun options that are $400-$600 depending on their fire rating, but often doesn't include shipping. Costco and Sam's Club have decent safes for sale sometimes but it's up to you to get them home and if you have stairs... good luck to you.
If you want a cheaper and lighter option, gun lockers aren't terrible. They can be bolted to the wall in a closet, are key accessible and have plenty of room for long guns. Stack-On is really the leader in this category and you can get one for as little as $120. Unfortunately these can be defeated with a little alone-time and a crowbar.
Trigger locks alone are trash, your gun can still get swiped. But if that’s all you got, it’s better than nothing. I have a friend who uses a filing cabinet with a hasp and a lock, it's pretty ghetto but it cost him almost nothing and it works.