Just an FYI. The mini 3 is going to be $300 all weekend at Best Buy -- yet more signalling that a new mini is coming from apple. I am trying really hard to not buy one, I don't do apple either, but we'll see.
The ASUS 580CA is interesting for $300, as is the recently announced Predator 8. I am heavily invested in the android ecosystem, I hate the idea of a 1-off mini . . .
Regarding the iPad Mini 3, you are correct...it is only $300...BUT, that is ONLY the Wi-Fi version. The cellular version is also $100 off, but, even on sale at Best Buy, it's still $430. The cellular version I picked up wss $300, saving me $130 off Best Buy's "sale" price, or $230 off their regular price. Like I said, you can find brand-new 16GB cellular-connected iPad Mini 2 for only $300 (give/take a few $$$), if you check Amazon.
As for the "heavily invested in the Android ecosystem", the same applies to me. I have a Galaxy S6, Asus ZenPad S 8.0 (Z580C), Nexus 7 (2013) LTE, and Galaxy Note 10.1 (2014 Edition)...plus I have an Asus ZenPad S 8.0 (Z580CA) on pre-order from B&H Photo.
Either way, I wish you luck in whatever decision you make. I dislike Apple almost more than anyone I know, yet, where a tablet for my P3P was concerned, in the end, I chose to make the intelligent & logical decision, and ignore my feelings about Apple.