Provide cost estimates for hardware

[legoktm]

Describe the change

We have a list of necessary hardware, we should also calculate rough cost estimates for each item to give newsrooms a better idea of how much it'll cost.

[nathandyer]

@legoktm We have cost breakdowns in the overview: https://docs.securedrop.org/en/stable/what_is_securedrop.html#cost

Do you think it would be sufficient to link to that from the hardware guide? Or should we list an approximate price for each item on the hardware guide?

[legoktm]

Sorry, I don't have an answer for you. This is just feedback I copied out of when we were drafting/reviewing the 5 things to know about SD blog post.

I do think we should probably recalculate that number (the blog post said $2,500), especially given we are pushing SDW.