Personally, I'd keep the Austins, rotating them until all the tyres are down to around 3mm. By that time you'll need tyres anyway and should have saved enough money to buy your wheels of choice. Don't sell the Austins, they can go back on when you sell the car with useable tyres on them. You'll then still have your chosen wheels to go on your next car, or sell.
One of the problems with todays 'I want it now' society is that what initially seems like a good plan, ends up costing more long term.