Hv you cansidered the Sherwater Predator OLED PROT-SA?http://www.shearwaterresearch.com/pages/3730/1145-shearwater-predator-oled-prot-sa
It is one of the cheapest and versatile tech computer that I've tried or played with till date. Most local PSAI divers and Instructors I know are using this unit. It uses VPM-B Decompression Models (Modified ZHL-16C with Deeper Deco Stops) which can be unlocked to incorporate the original ZHL-16C's longer shallow deco stops for those who feel more comfortable this way or if the individual school of instructions demands so.
Another Plus Point is its colorful OLED screen... It first caught my attention on my AOW Night Dive in September when my usual instructor, Jack Lim from Scuba Warehouse, was wearing it in the water while he was teaching his tech diver trainees...
Quoted off DGE's Website:
The VPM-B unlock code enables the option of using the Varying Permeability Model (VPM-B and VPM-B/GFS) algorithm for calculating decompression. The CCR unlock code upgrade adds several features to support rebreathers including the ability to perform constant PO2 set point calculations for deco. This software feature upgrade allows any Shearwater Predator model dive computer to be switched between a choice of VPM-B, VPM-B/GFS or Bühlmann ZHL-16C with Gradient Factors decompression modeling algorithms.
Local Authorized Dealers Scuba Warehouse ans Waikiki are selling it at about SGD 1,400 (Price Controlled by Manufacturer) and I think it comes with some form of training, Desktop interface and upgrades in firmware.