the cheapest way of getting over 140 amps at 12v in the UK may be to get a couple of
Dell Poweredge 6650 900W power supplies.
You should be able to get two for £32 shipped.
Wire them in parallel to get 144 Amps at 12v(1728w).
The fans are very very quiet.
If you only want a single power supply then you may try the IBM xSeries 366 1300W PS.
It will supply 108.1 Amps at 12.2v(1318W).
The price is around £24.99 shipped.
This thread started by jj604 has all of the info you need on how to power them up.