Laptops are anywhere from NTD35000 to 80000, depending on brand and model. I rekon for a good one you need to spend around 45000 - 50000. I use an older Asus laptop at work and I am very satisfied with it - no problems running WindowsXP and Linux on it.
At my former company I used IBM laptops, again no complains but made some bad experience with Compaq before (long time ago though).
If you want to be mobile then you should opt for a processor with reduced power consumption, typically a Pentium M. If mobility / battery time is not so much of a concern but rather performance you may want to chose a laptop with a standard Pentium processor.
Choice of processor, RAM and other features (CD or DVD, size of harddisk etc.) will influence the price. To get an overview go to TKEC (the yellow 3C computer store) and get their latest flyer which lists lot’s of laptops.
Bluetooth support is not really common yet but I remember I saw at least one model on the flyer that had it.