I've looked closely at the Autoglym alloy wheel cleaning products, including their chemical composition from the SDS sheets. I don't think their retail 'Custom Wheel Cleaner' is exactly the same as the JLR recommended product (Range Rover Alloy Wheel Cleaner VPLSW0066) which is also made by Autoglym. The latter is available from JLR dealers, but is naturally quite expensive. However, a cheaper source is from 'shop4landrover.co.uk', £9.90 for 500 ml, postage free.
http://www.shop4landrover.co.uk/product/..._VPLSW0066
The same JLR approved product is also sold to the trade as Autoglym Professional Wheel Cleaner and is available from trade distributors in bigger (e.g. 5L) quantities, and presumably at much lower cost. You can find out about this product, and search for a trade distributor in your area on the Autoglym Professional web site
http://www.autoglymprofessional.com/en/p...el-cleaner
Hope this helps