I will explain later, but basically, when I moved laminar flow hoods to Viet Nam, one broken severely. It was a US$14000 equipment, the 2.8m one with vertical and recycling.
I discovered that there are 3 blowers (because it is a wide one), 1 pressure gauge, 1 rheostat to control the blower speed, and the UV light (optionnal I would say). Basically, the 14000 equipment was cheap metal and the above mentionned equipment ( Made in China for the blowers, as I found out).
For HEPA filters 116cm ( for the 120 cm hoods), I paid for the spare part 320US$ ( but I wanted a special class) for a new one. I check, and the price in the Netherlands for a Class 100 HEPA are around 180-220$. Some filters are US$140 only from another company. A blower of very high quality is about US$180 ( Korean one) or US$80 (Italian). So my guess, if you know how to cut metal and build a metal box, is that you can have a LFH for 500$ all included, for the very high quality one. I will put a scheme of the one that broke, you will have to follow it, and you have a vertical flux recycling laminar flow hood...