Gadget makers including Apple and Google have been accused of ripping off customers with overpriced tablet storage upgrades.

Choosing between tablet models typically means deciding whether you want mobile data or not, and how much internal storage you want. However, Which? reports that consumers are getting a rough deal when it comes to paying more for higher storage capacities. See also: the 15 best tablets of 2013.

For example, the entry-level iPad Air costs £399 for 16GB and you'll have to pay an extra £80 to double this to 32GB. There's no memory card slot for adding more, like many other tablets, so picking the right one is important.

Which? claims that the memory upgrade only costs Apple £6 making the upgrade a mark-up of 1,267 percent.

"16GB of Flash memory is mind-numbingly cheap now," said Ben Miles from PC maker Chillblast. "As a general rule, for manufacturers like ourselves, Flash costs less than 40p per GB, so for companies to charge so much for an extra 16GB seems scandalous."

Google and Amazon charge £70 and £40 for the same upgrade for their Nexus 10 and Kindle Fire HDX 8.9 respectively. The mark-ups aren't as bad when compared to Apple but still represent a big jump compared to the market price for memory.

Which? editor Richard Headland, said: "With tablets in demand this Christmas, buyers will be shocked to discover what a raw deal they're getting on built-in memory. If you want the best value storage, then buy a tablet with a SD or microSD slot and add a memory card for a fraction of the cost."

The other issue with storage is the fact that users don't get the advertised amount. This blew up significantly with the Samsung Galaxy S4 which touted 16GB of storage but less than half was available to the user due to the space taken up by the operating system and pre-loaded apps and software features.

Which? recommends buying a tablet with a microSD card slot for adding your own storage or considering using internet cloud storage.

Do you feel like you're being hard done by, or do gadget makers have no option when differentiating between models? Let us know below.

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