There are a lot of good choices already mentioned, so I will suggest one company to steer clear of. Center of Mass sells simple key operated lock boxes for securing a pistol, and since I wanted simple box for air travel I bought one.

When I got it is STUNK like petroleum waste. The foam inside was saturated with the smell of petro-waste products and it was so bad that there was no way I could put it into my suitcase. The company seemed initially receptive to correcting the problem but in the end told me I should go buy new foam since they didn't have any. They were buying their lock boxes from China and I guess one way to get rid of your industrial waste is to sell it to Americans. I think the company should have stepped up and replace the foam; I don't have a source and I don't have the right tools to die-cut the foam.