Hi.
I've tried to do exactly the same thing with the remotes for my roller blinds, I also started with relays (as they are the most obvious solution), but I found something that works just fine, no noise and low power:
http://www.ti.com/lit/ds/symlink/cd4066b.pdf
Just power it with 5V (I think it works from 3 to 18 V) and you have 4 "switches" using pairs from the IC and send a "high" state using a control Output from the arduino to the control pin on the IC, it doesn't really "connect" the two contacts, there is still an small resistance between them (about 500 ohms) but it works just fine with my remotes, they think the button has been pressed.
And, as a bonus, they only are about 1.50 euros for 10 PCs, that is 40 switches for 1.50... try to do that with conventional relays and you are looking at about 45 euros at least.
Regards.
PS: Also, they work with the Relay example from the libraries, just changing the default value from #define RELAY_ON 0 and #define RELAY_OFF 1 to make they active HIGH, (#define RELAY_ON 1 #define RELAY_OFF 0)