thx for ur feedback
seems like the contractor is not fooling an outsider like me 

however, he quoted me for rm1500 for installation alone, the cost includes:
35ft cabling, hacking the current cement ground, embed it in the ground,
resurface with cement again and install arm gate system

not including re-tiling (will be getting new tiles later on)

Those price u guys mentioned, does it include the gate itself?
Else how much they cost for the gate alone?

You'll need the following wires for a typical swing arm installation:-

1. 3-core 240V AC from power source to gate control box.

2. 2-core low voltage signal wire from control box to inside house for gate push-button switch (this is optional, if installing this switch is going to involve hacking and ugly conduits all over the place, then just use the remote)

3. 3-7 core low voltage wire from control box to left motor.

4. 3-7 core low voltage wire from control box to right motor (could be under driveway from post to post). Wiring Diagram

5. Optional : 2-core low voltage wire from control box to solenoid lock. (routed within the gate)

The material cost should not cost more that RM200 -RM300 (wires, conduit, joints, switches, cement etc), all in I would say for a medium size gate if the work can be completed in a day it should not cost more that RM500-RM700.  If this work was undertaken by an Autogate installer they'll just factor it in as part of the installation and quote an incremental lump sum