900mhz
Panasonic KX-TC1743 $89.99 at Staples
2.4ghz
Panasonic KX-TG2583W $149.99 at Staples

the 2.4 is obviously the main difference, the 2.4 ghz unit is also shock and splash resistant.

Brands I highly reccomend you avoid:
Siemens
Sony
Toshiba

Any more Q's let me know, I have the privilage of selling these things all the time :p

-Pete

Every time I come online I wonder if the forums will be up