As the kalzumeus blog would say about pricing, base your pricing not on how much it would cost you, but on how much value your product gives to your users.
Based on your recent post about your specific target market (Wall St.), talk to them. Based on your recent post it seems that you're doing high-volume B2B transactions. If you ask HN about how much we would pay for that, you would get lesser value from our answers since we would compare your hardware offering to EC2 instances, which I guess, isn't the type of market you're after.
Talk to the Wall St. guys you're targeting, call them up or send them an SMS, grab 30 minutes of their time and treat them out for coffee. Don't ask them how much they'd pay for it, instead, spark up a conversation about what they're currently using and if you're lucky they'll tell you how much they're spending for it. Watch out for keywords on what they value. You can charge more by offering what they value.
If they value SLA's, high-level support and a specific amount of latency, charge based on that.
After talking with them, tell them and their IT team to subscribe to your mailing list which will not spam them, but educate them about handling financial data coupled with your hardware.
Gain their trust from your expertise, close sales from that mailing list once you launch.