Normally the contractor will visit the site first before they give an more accurate quote. Else, there could be arguments later.
I have been quoted RM 300 for conceal air con piping up to 1.5HP for length of 20'. This involves a lot of hacking work. This is for non inverter.

For inverter will be much higher because of the min thickness of the copper piping and additional control wire.

don't think you will accept the plastering quality from the air con workers

If it is for inverter, then should reasonable. There are additional control wire from the compressor to the blower unit for inverter A/C

Sometimes, the charges may be a bit different depending on the site condition. Landed property or condo?
In the balcony, can use the PVC trunking. This copper piping can be hidden inside the trunking.
The trunking painted the same colour as the wall. Looks nice...

Have you tried asking your aircon supplier to quote you for the piping? At least you have a comparison.

1k to relocate 2 aircon is damn expensive. Have you tried asking
those electrical shops that are sell aircon to quote you?
Maybe it include cleaning and pumping in gas for the aircon as well?

Anyway, for easy of mind, better to get another 1 or 2 quotes.