+1 on the driving over the train,
That said, if you still want to take the train, consider taking Amtrak or SEPTA to Newark, DE. Service is less frequent, but it is much closer to Christiana Mall than Wilmington. It's also a nice college town.
There is also a cluster of big box stores at US 202 and DE 92 near the PA - DE Border. No Apple Store the last time I checked. You could Uber / Lyft from Septa's Claymont Station or there may be a bus from Wilmington.