1) Cost share with other PPLs or passengers
2) Ask schools if you can do positioning flights - for maintenance or whatever.
3) Boatpix - as mentioned by Squirrel
4) Fly B206 in LA doing Traffic Watch - around $130/hour, though that may be out of date by now.
5) Go to South Africa, New Zealand, or anywhere else with cheaper flying and a good exchange rate for the £.
That's all I can think of for now.