I have seen them. Personally I would not buy one. I have far to much invested in my firearms to trust there safety to a safe with no fire protection or much in the way of theft protection.
I agree. To the OP. You will reach a point where it doesn't make sense to put your guns in a cheap safe. A safe is, by definition, a place where you concentrate all your portable material wealth.
If you have $10,000 worth of guns, it seems foolish to me to put them in a $500 safe. But thats just me. Remember that if you are broken into, the thief will focus their efforts on any safes they find.
So in my mind, if you don't have kids, you are better off hiding your guns very well than you are putting them into a cheap safe. In fact, a cheap safe as a "honeypot" can be a very useful way to waste a thief's time.
Another option is to buy one of the many VERY VERY secure business safes available for pennies on the dollar from Craigslist. These safes dont have nice interiors or electronic locks. You put your valuable stuff in there and only put the stuff you shoot regularly into your "everyday" safe with an electronic lock.
A buddy of mine has this setup. He's got a TL-30-6 safe hidden that has his machine guns, suppressors, and custom 1911s as well as his nice rifles. His everyday safe is a canon places somewhere convenient to him with a couple of Glocks, a 1911 an AR and a couple of .22s. Total value in the nearly impenetrable 4000 lb safe is probably $40K. Total value in the every day safe is probably $2500.
Don