Can I just make the point that MOST of the Supras sold on here in the past few months (this "avalanche" of sales, apparently) have been sold for reasons other than basic running costs.
Yes, they can be a thirsty car but no more than any other 3 litre petrol engine (and a damn sight more economical than some) if driven judiciously. And yes, they are expensive to repair and replace parts... but these parts have usually lasted 14-19 years!
Bottom line, you get what you pay for. Stop thinking these are £10k cars, and start thinking they are often poorly maintained £30-40k cars (the exceptions being the no-expense spared restorations like Dandan's full suspension replacement) and you'll keep your expectations appropriate.