Sounds like you bought big one (36 inch). Because of space considerations, I needed one to fit in the window, which meant the 24 inch "Super-Mini". I had to do a lot of "re-engineering" for that installation, and I was very unhappy with the lighting in that particular model. Those things aside, I've been very happy with its performance. I did a lot of research on what was available, and this brand seemed the most practical, but they are rather pricey. On the up side, they use readily available furnace filters. Filters can become a big expense if the booth requires OEM. It's a big investment, but it's worth it for the sake of your lungs, liver, and kidneys, and your heirs will inherit it.

"Portable" booths are much smaller, and not all vent outside. Many require specific filters. Unless you are doing 1/72 and smaller, I don't recommend any of them, even though they are much cheaper. That said, it might pay you to shop around.

I've also seen ones that don't vent outside. I consider them unsafe, period.