Both Erik and I answered that before:
Erik - http://www.8052.com/forum/read.phtml?id=82296
Me - http://www.8052.com/forum/read.phtml?id=82298

So, one more time:

As Erik said: if you save the money by not buying the dev kit, you will have to spend the time doing the design, build, test, debug, documentation, and support all by yourself.

And remember: the dev kits are designed, built, tested, documented, and supported by people who are familiar with the chip - I get the impression that you will be starting from scratch with no prior experience of the chip?

You need to ask yourself (and probably discuss with your tutor) whether the main aim of your project is to design & develop a piece of working hardware, with just a little simple software to demonstrate it, or whether your main focus should be a significant software development.
I think doing both in the 5 months that you have available may be a little ambitious? (especially if you still have other coursework to do).

If you determine that your main focus should be a significant software development, you'd probably be better off looking elsewhere for low-cost ready-made RF modules - there are plenty about.
Maybe infrared would do for the purpose?