If you want to just use waze/spotify, you don't need mirror link. Just Android Auto. Cheapest Android Auto supported HU that I bought was this
Note that this also says that it supports mirroring. but honestly I don't use it because Android Auto is more than enough


7862 seems to be going up in price, so RM900+ ish seems about right. I bought mine before Aidilfitri for RM800. Can't find this price anymore :V
If you want something cheaper, TS18 player are around RM500~RM600. I would recommend this if you are not using 360 camera as the 3GB model is more than enough for daily use.

For installation. the rule of thumb is RM60 = install head unit + RM60 = install rear view camera.

its like a phone. where chipset is sell by the chipset manufacturer, eg like qualcomm produce snapdragon 8 series of chipset, together already with modem chip, wifi, bluetooth chip etc. and phone manufacturer ( xiaomi, samsung, vivo, etc) take this hardware, put their own design and then use google android source code, compile their own skin  addon their  special features etc.

7862 and TS10 have same chipset, same cpu, radio chip, sound processor chip etc. but both have diff firmware, and diff display screen. and this chipset, seem use by diff android manufacturer company and put their own branding, even those its the same things inside. even firmware also same. and some have customized firmware and product package with proper warranty, better OLED display eg like the Teyes company, hence by the price for this teyes CC3 is much more expensive than generic brand that use same 7862 chipset.