How Much does the Treasure Act cost Britain Annually?

On a metal detecting blog near you, metal detectorist Bill from Lachine (Montreal Canada) ponders the deeper meaning of the UK's Portable Antiquities Scheme and wonders about its costs. He struggles to rationalise it like this (February 4, 2014 at 6:11 pm ): 

I’m curious as to the total finds declared treasure under the PAS system what the total costs were of purchasing these items versus the total finds recorded under the system. I’m thinking it probably works out to less than $1.00 or 1 pound per hours expended time and energy not counting equipment costs, gas, etc…pretty cheap labour versus the payback in my books. 

First of all it is not "under the PAS system" that finds are declared Treasure, this is a totally separate process involving the Coroner and then the Treasure Valuation Committee (to which PAS only provides a supporting role). What an odd suggestion, that a FLO can work for less than a dollar an hour. Forty dollars a week for a UK professional? I cannot really see many takers there.

from the 2010 Annual Survey of Hours and Earnings (ASHE) via wikipedia

Mr Lachine seems not to realise that the PAS salaries and administration costs are paid, not from Treasure awards, which go elsewhere, but from the public purse, to the tune of 16 million quid so far. This covers also their travelling costs and expenses when they visit clubs and rallies.

So what are the total costs to the taxpayer of buying back from greedy artefact hunters (who "aren't in it for the munny" you understand)? Well, oddly enough the amount of money made each year by their "partners" from hoiking and sale of Treasure and non-Treasure artefacts is nowhere collated by the British Museum's PAS and Treasure Team. The annual sum is however enormous with 8-900 being reported each year (though many are disclaimed and the artefact hunter gets the finds back to flog off or hide away).  Let's have a look at a few found by metal detectorists and declared under the Treasure Act:

Bedale Hoard cost the nation’s museums £50000
Bitterley Hoard cost the nation’s museums up to £30,000
Bredon Hill Hoard cost the nation’s museums £40000
Collette Hoard cost the nation’s museums £???
Frome Hoard cost the nation’s museums £320,250
Stanchester Hoard cost the nation’s museums £50,000
Furness Hoard cost the nation’s museums £??? 
Hallaton Treasure cost the nation’s museums in excess of £785000 
              (plus the costs of conservation of the helmet)
Milton Keynes Hoard cost the nation’s museums £290,000
Newark Torc cost the nation’s museums £350,000
Ringlemere Cup cost the nation’s museums £270,000
Sedgeford Torc cost the nation’s museums £3,300
Shapwick Hoard cost the nation’s museums £265,000
Shrewsbury Hoard cost the nation’s museums £????
Silverdale Hoard cost the nation’s museums £110,000
Staffordshire Hoard cost the nation’s museums £3.285 million
Stirling torcs cost the nation’s museums £462,000