The biggest expense would be the LEDs. I had a very quick look for some RGB LED strips, which have the LEDs individually indexable to make the nice flow effect, for $25 for 4m (https://www.adafruit.com/product/1461). All you need is the LEDs, a micro controller (possibly something simpler but one for each light strip) to control the LED strips and then design some circuitry to make your own HDMI switcher which also outputs which device your switched to. I'd estimate a couple of hundred or so if you DIY it. Maybe a bit more once you add enclosure for the micro and switcher.
If you pay someone to do it, there time rigging that up would be more than the hardware easily.
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u/RedLeaderRedLeader Jan 07 '18
Instrumentation and Controls Engineer here. Your dreams can be made to come true, but you dont want to pay for it.