You can "clone" some mushrooms pretty easily. Oyster mushrooms and shiitake tend to be ageessive enough to out compete minor contamination (depends on where you live as to what contams are around). Make multiple slides. Pick the clean ones to move to grain spawn. One or two dishes in a quart jar of grain spawn. Don't expand too quickly/far - look for inoculation rates over 10% of the substrate mass when moving to fruiting substrate.

That said, just a dead air box/bag/room with lysol aerosol disinfectant (ethanol) for the trapped air and 70% isopropyl alcohol for surfaces is fairly effective. I'd be careful with fumes. I have a basic respirator like a 3M 5xxx or something.

I also tried a combination flowhood/glove box type thing. It works well if you have a new filter or leave it on. Otherwise, I think contamination just gets blown off of the filter once you do turn it on again.

I didn't mean for it to even go this deep. You don't need to actually culture the mushroom from scratch. You can buy syringes with liquid culture. Then just squirt it through the bag with sterilized grain spawn (pressure cooker can sterilize). Then transfers to the fruiting substrate can be done in a moderately cleaned room without any special devices using the aerosol and wipe alcohol with inoculation 10-20%. This is surprising effective, even for contamination prone stuff like lions mane (which I can never seem to culture from spores myself).