Michael,
Tempo has the e-mail notification already in the system. You have to enter the new prospect, create a custom search based on your prospect needs and the system will send e-mail notifications whenever a new listing match your custom search. Notifications are sent once a day, usually early morning.
No additional costs, no headaches. Simple and easy.
Tarasoft has a good system too, and works very well with ARMLS. I think the cost is $299 for 2 years of updates.