[UPDATED] CALC - Would This Be Useful?

Search awarded hourly rates for labor categories
CALC lets you conduct market research on professional service labor categories more quickly and easily. It also takes the guesswork out of cost estimations — all results shown are actual awarded hourly rates from GSA service schedules — helping you make more informed decisions.

https://calc.gsa.gov/

And if NZ Government (local, regional but particularly central) think this is cool - go for it, the code from the US Government is free and available here: https://github.com/18F/calc

[Update: added 15-May]
From +Nick Williamson's tweet to us we had Spend Network from the UK come to our attention:

We're a small team that have been working with public procurement data for over 12 years. We've grown tired of waiting for Government data on spending and contracts to be compiled into a useful tool, so we've decided to build a solution ourselves.
What are we doing?We're building a business for both Government and suppliers to Government. We believe that Government shouldn't have to pay for spend analysis, as long as the data is open, and that suppliers need better data on Government opportunities. If you'd like to know more about what we're doing and how we work, we'd be delighted to tell you more.

https://spendnetwork.com/