DBX Space Saver Spare Wheel

[Stevejay]

Recently bought a DBX 550 and loving it, ticks all the boxes for me. My wife and I have a road trip planned for August this year, 3000 miles down to Gibraltar into Portugal and back. Travelling that distance thought it best to get a Space Saver Spare Wheel. Aston Martin want over £1300 just for the wheel and tyre, to buy the complete wheel kit with jack is over £1800.Aston bits have a second hand one but they want £800+. Diameter of Space Saver is 21 inches. Is there a knowledgable person that can tell me an alternative wheel that will fit and be safe to use at a fraction of the AM cost. Many thanks in advance.