The Mal's E-Commerce shopping cart was offering a deal for daily HackerSafe scans for about $20/month (total cost) for life if you registered for it through them. Don't know if they're still offering that, but that's how I got it. The LinkPoint shopping cart offers the same deal.
Personally I don't think it's helped my business, it's just caused my webhost (who's very security-conscious) a world of trouble fixing things that aren't really problems. They once forced him to tighten things up so much that they couldn't scan the site at all. When that happened they prevented the HackerSafe button from showing for several days. My sales were very good- even a little better than ususal. I'm thinking of cancelling it.
Sticking 'HackerSafe' on a web site is like showing a red rag to a bull, IMO - it's just inviting unwelcome attention. You would be better off with a scheme that takes a broader view of online security and emphasises protection for your customers, rather than protection for your site.
I'm not sure where you are based, in the UK we have SafeBuy (http://www.safebuy.org.uk) and ISIS (www.imrg.org), there may be something similar where you are.
BuySafe is a good and the cost nothing as the customer purchases insurance but the company checks your business out and you have to have a cc on file with them to pay the charges that your customer buys. You actually make money as well cuz the insurance is split.
HackerSafe and it's ilk are a complete waste of time and money IMHO. I had ScanAlert call me a couple of times and I actually ran 2 separate A/B tests on my site, and having the "HackerSafe" logo on my site made absolutely no difference at all.
I ran my own test by the way, not the one they wanted to setup for me. I'm sure that theirs would have shown a difference ;)