Cost-effective storage for prototyping In my project I need to add some storage space and I don't want to use an SD card, because in the "final product" the user shouldn't be able to access the data on their own.

So I was considering the options here http://playground.arduino.cc/Main/InterfacingWithHardware#Storage but many of the technologies are either outdated, for example as reads here ADESTO is discontinuing production of dataflash, or they give too little memory, like the I2C EEPROM (which is 128KByte per chip and I would rather not go through the hassle of multiplexing lots of memory chips since I'd like to have 1MByte of storage at least), or are extremely overpriced and cannot be found on retail: some sites require you to buy 2000$ worth of chips or charge you 30$ for delivery, which kind of kills the fun of prototyping something.

I know I am being picky not wanting to use an SD for the prototype, but I would like to know if you ever faced this problem and how you solved it, or if you know some alternative solution which gives a good amount of memory (~1 or 2 MBytes at least) within reasonable costs.
You may not want to hear this, but the cheapest option would be an SD card, or a micro-SD card. You could solder it into place, thus making it quite hard for the end user to take it out and plug it into a reader.

Imagine you had this micro-SD card glued onto your board (making it hard to remove in the first place):



It isn't particularly obvious what it is, unless you recognize the shape. You could cover it with a blob of plastic to hide that. Then with the SPI wires soldered to the contacts, removing would be even harder.

That gives you gigabytes of storage, a file system, the works. And all for a few dollars.

A technically sophisticated user could probably prise it loose and get at the data (although if you used strong glue this could be quite hard) but they could also get at the contents of another storage chip too.