I can never find it available and I want to dive into IoT projects, but the wifi shield is never available.
The WiFi101 Shield together with the Arduino Zero makes for a nice development platform. However, at a price around $100 this seems to be a yesterday product. The Arduino MKR1000 at around $35 provides the same capability (except for lacking the Atmel EDBG chip, not supported anyway by Arduino).
The ESP8266 boards and shields from Adafruit and SparkFun provide similar IoT capabilities (except for lacking the Atmel Crypto chip, also not supported by Arduino). So dive in, just pick a newer platform.
I have a couple wifi 101 shields. If you'd like to purchase one from me, feel free to message me.