I have a Transformer TF101 which I got second hand several months ago so I paid about $200; I believe it would be cheaper today. I am very happy with it, but I did get a dock recently because I found myself typing a lot, and while the on-screen keyboard is good, a physical one is better. You can definitely pair it with a bluetooth keyboard, but where I live it would have cost me more to get one locally than buying the dock online, so I can't say anything about the connectivity.
I found it's a very stable tablet, with long battery life, but they could have provided it with a longer charger cord. It has a slot for a micro sd card up to 32 GB. WiFi is excellent; I use it at my uni and it picks up all our networks as well as some of the surrounding ones. It has Google Play access, as well as Google Music and Movies, and a Netflix app if you're also interested in using it for entertainment. I can't due to my location. There's a Polaris office app which can read and edit Word, Excel and PowerPoint documents (.doc, not .docx). I presume a .txt app could be found on Google Play.
If you do get the Transformer with the dock, it might be good to know I was also able to connect a 250GB hard drive (WD) to it and could access files, play music and videos. I hear people were able to connect 500GB, or even 1TB hard drives.