KNX is a standard not a brand, hence you can just say KNX costs 10 euro or 1000 euro. KNX via an adapter can control regular lights, at least on/off not sure about dimming. But KNX is best used with compatible lights, which means you need special lights and different cables. I think in my appartment there are two cables, I assume one is for control and the second is the regular power source. For example some companies that in my opinion have good products are BAP Tech (https://www.bab-tec.de/), Gira (https://www.gira.com/en/gebaeudetechnik/systeme/knx-eib_syst...), Jung (https://www.jung.de/en/820/products/technology/knx-system/) ... to find companies near you I would recommend using the official KNX website: https://www.knx.org/knx-en/for-professionals/community/manuf.... the system for the lights is called DALI (https://en.wikipedia.org/wiki/Digital_Addressable_Lighting_I...), for example OSRAM has a Dali/KNX website here with more information: https://www.osram.com/ds/highlights/knx/index.jsp ... to find prices I would recommend using a website like https://www.eibmarkt.com/ (set the country to United States and the currency to US Dollar)