Rates have gone up in most of Oz for my rentals in the past year, but not >100%. Europcar is showing AUD 400 per week for Camry at airport Feb 1-15 (cheaper elsewhere), which is GBP 200, and their cheapest car (Hyundai i20) is AUD 250 per week or your 2014 price. Supply/demand affect prices a fair bit in Tasmania due to cost of repositioning fleet and managing to keep from having excess inventory.