The $300 one is a GePe 8x12" Lightpanel. Custom make is not difficult, just tedious. And if you are serious, you should really be getting 5000K floursecent tubes, preferably flicker free ones.
5000K is not enough.
As important or even more important than that is the CRI rating.
Colour Rendering Index is the discribetion of now close the the spectral distribution is to natural lighting.
Natural lights has a CRI of 100%
You need CRI of >90% for slide viewing by IEEE documentation.
This was the one of the reason why Floursecent lighting was not used for photography.
CRI 92% tubes are quite affordable if you can find them, and 98% is better if you can find them.
flickering is not the problem of floursecent tubes, it is the cheap traditional magnetic ballast that is at fault. You need to get a electronic Ballast which is inverter driven.
Color corrected normally means 5000-5500K with CRI >90%
"Daylight Balance" is much more blue than that, it is about 7500K-8500K.
Tubes labled as "Daylight Balance" will never have a high enough CRI rating, it can range any where from 65-85%, which is simply not good enough for colour rendering.
