Just get some rechargeable batteries and a charger.
MX3000 is a LED Mouse (MX700+Elite KB), the MX3100 is the laser Mouse (MX1000+Elite KB).
Not sure why Logitech site for drivers has MX3000 as laser and MX3100 not laser.
I have had both so its back to front.
The MX3000 also has a laser mouse (MX600), as seen here:
http://techgage.com/article/logitech_mx3000_cordless_desktop/2
That said, I have a feeling there was a version before it that only had a standard optical mouse. Can't remember though.