The Gekko or Nitek duo dive computer are both great, low cost, easy to use computers.
The Gekko is a bit more conservative (and requiires it's users to follow the rules very carefully or it will reduce you dive time)...but both work well.
The Gekko is a bit more conservative (and requiires it's users to follow the rules very carefully or it will reduce you dive time)...but both work well.