You actually made a smart move putting off a purchase.
You definitely want to bolt it down, but you also want to spend some $$$.
This is a video a friend shared with me a few years ago. It's one of the most informative sources of information on gun safes I know of. He covers a lot of information, he misses some things I would consider important, but it's pretty comprehensive. Remember that all a safe does (all any security does really) is slow people down, and increase the skill or force they need to break it. You can do a few simple things like where you position the safe to increase security dramatically, so put some thought into what you're doing. Finally, it really is an investment. If you have $50,000 in guns and valuables, there is no reason you shouldn't be spending $10,000 on a good safe. If you have $20,000 in guns, you shouldn't be wasting $500 on a crappy safe - which, a $500 safe will stop most common criminals if you bolt it down, but it won't stop anybody that is determined, and it won't even begin to stop somebody that knows they're breaking a safe and knows that there is a $20,000 payoff. There are videos on how to break in 10 gauge steel safes on YouTube, so just about anybody will be able to get into your Stack On from Wal-Mart if they get their eyes on it and identify it, and look into how to go about getting in it.
[video=youtube;ltK-bDbADa8]https://www.youtube.com/watch?v=ltK-bDbADa8[/video]