John Deere's Aluminium JA62 and JX75 Lawn Mowers
Aluminium lawn mowers are more expensive than their steel peers because they don't rust and the cast alloy is less likely to crack. Is it worth the expense though? I guess it depends on how you plan to use your mower and how long you plan to keep it for. If it were a mower you plan to hand on to your grandchildren then aluminium would be the way to go. However, if you plan to replace your mower every 10 years or so then you may find the additional price for an aluminium cast deck is unwarranted.
For those who like the aluminium decks you might want to check out John Deere's new 21-inch offerings. The JA62 and JX75 models look fantastic and coming from John Deere you would assume they're going to last the distance.