I much prefer the reader/writer combo although the magnetic strip spoofer
http://www.instructables.com/id/Magnetic_stripe_card_spoofer
is cool, although I personally like to go to www.dealextreme.com and grab some magnetic cards they look much less incriminating when in real world applications.
dealsextream.com has some readers and reader/writers but they are not worth buying I have had some bad experience with items I have bought on the website so I wouldn't take the risk you might have better luck on sparkfun.com
In conclusion you should go with a expensive modal if you are looking to get some good use out of it
An interesting project might be it may teach you more about the whole process of reading and writing magnetic cards
http://www.instructables.com/id/Arduino-magnetic-stripe-decoder/
