I use a device called an IT watchdog minigoose 2.
http://www.itwatchdogs.com/product-detail-minigoose_ii-8.html It has an additional water sensor
http://www.itwatchdogs.com/product-detail-water_sensor-36.html which you could fix at a given height in the sump to detect water.
This is capable of many things including remote monitoring, temperature sensors etc. Expect to pay about $240 for the sensor and the minigoose to get the email alerting (also does SMS and SNMP alerting and has a neat web interface so you can manage it remotely).. I love the device and I have temperature sensors monitoring all kinds of things including the ground temperature for geothermal, attic temp, water sensors in critical areas.. a perfect solution and a cheap reliable one at that.