The choice is yours. You can look on ebay, or amazon, or google, or try to find a good deal locally. It is up to you to decide what you need and to find the best price, and then to decide if you are willing to pay it. You can find an MCE receiver with a remote that is still fairly inexpensive. If you find one with no remote control included it probably won't cost much less anyway.
You can ask Amulet Devices if they sell an IR receiver. They used to have the option to get one with your remote for an extra fee, but I don't see it on their site.
All the information you need about EventGhost is here:
http://www.eventghost.org/If you are using an MCE remote, you don't actaully need EventGhost, it will mostly work out of the box in Windows. You only need EventGhost if you want to customize the buttons. For example, by the default, the green windows button will open Windows Media Center.
If you also want to
control your audio-video equipment then you should consider getting a UUIRT instead of an MCE receiver.
http://www.usbuirt.com/ It costs more but it is much more flexible.