Arduino SD and Micro SD adapters, why such a big price difference?

So, I was looking on ebay and I got my regular SD card adapters for less than $1, however, I looked at micro SD adapters and they are a ll at least $10! Why is there such a huge price increase? It makes no sense.

The sense is that the SD card adapters are larger and older and so the cost of the tooling has long since been payed. The newer adapters are more difficult to make and are still paying off the tooling costs.

Having both bluetooth and wifi modules will add a lot to the cost - you're likely talking a $100 card. Did you have a couple of specific modules in mind?

Wifi modules - $20-30|0
Bluetooth modules - $10-20|0&FS=True

The rest of what you describe is just a mega layed out a little differently with RTC chip, uSD socket, 5V to 3.3V converters & power source for the uSD. Need I2C or SPI for RTC, SPI for uSD, maybe a serial port each for the RF modules, Rxo/Tx0 for USB communications. Leave 1 free for other user use.

Having 2 RF modules is a conflict with requirement #10.