If you are cutting Acrylic, the activated charcoal filter is really the best way to go.
You might want to look into the smaller units used in nail salons, the HealthMate 200 made by Austin Air Purifier's would be an example. These are usually much cheaper (especially surplus) and designed for Acrylic fumes.
The problem is going to be the cost of replacement media, as the activated charcoal can be depleted pretty fast.
Electrostatic and HEPA filters won't remove the odor very efficiently if at all.
I suspect your friends activated charcoal filter has insufficient capacity (surface area) for the fumes, in which case it will be ineffective.