Hey Hussain,
You basically just need the reader of the RFM. I'll give you a short breakdown below.
The TMS3705 is a micro reader chip that needs just a few external parts, and antenna, and a micro (see schematic below). This reader is nice and cheap but all the communication protocol has to be handled on the micro. This can be quite tedious and time consuming.
The MRD2 is basically a drop in ready solution. It already handles all the software/procotal for you and can literally just dump the data over via UART/USB. We'll call this the medium priced option.
The biggest differences between the above 2 solutions and a RFM, is the power and cost. The RFM's are much more powerful, which means you can get much better range. They usually come in more of a RFM Module, then you also need a control module and an Antenna. This is usually the expensive solution, but if you need the range this is your best option.
I've attached 2 docs in the zip folder that show some range data for your reference, just to give you some idea of the difference between the uReaders and the RFM.
Thanks,
JD