Brisk Box Kit

Build a [box fan air purifier](https://www.reddit.com/r/crboxes/comments/1hi3z6h/portable_box_fan_air_purifier_with_shroud/). It's just as effective as some commercial air purifiers that are at least 10 times more expensive. You can use the money you save to build more air purifiers. If you want a quiet air purifier, your best bet is a [Brisk Box Basic Kit](https://www.cleanairkits.com/products/brisk-box) from Clean Air Kits. Like a box fan air purifier, this uses furnace air filters instead of special proprietary filters.

Jim Rosenthal (half of the duo behind the Corsi Rosenthal box) did an experiment comparing a Corsi Rosenthal box using MERV 11 filters against a high-end commercial air purifier using a HEPA filter. You might think that the MERV 11 filters (with lower filter efficiency than MERV 13 filters and MUCH lower filter efficiency than HEPA filters) would have been left in the dust (pun intended). In contrast, the cheaper and cruder Corsi Rosenthal box outperformed the commercial air purifier with the HEPA filter. In other words, the cheap and crude air purifier was MORE effective at cleaning the air than the expensive commercial air purifier.

I have a [Brisk Box](https://www.cleanairkits.com/products/brisk-box) running 24/7. You can choose your own filters to build it. I use the recommended 3M Filtrete MERV-13 filters, which don't seem to have an off-gassing issue. It's quiet enough that I can have a conversation in normal speaking voices while standing right next to it. And the 6-fan version uses only about a kilowatt of electricity every 3 or 4 days. It's not pretty (although you can put an artsy, gauzey fabric over the filters to dress it up) but it's very effective and economical.

Seconding air cleaners that use PC fans. The [AirFanta 3Pro](https://a.co/d/8LTLqZy) is great, but I admit a bit higher than the price point you mentioned. It moves and cleans the air quite efficiently even on the quieter speeds. I'd recommend buying from AirFanta/Adam Wong and avoiding the copycats. Clean Air Kits also has a [4-fan Brisk Box](https://www.cleanairkits.com/products/brisk-box) that does its job very quietly and consistently. I overlook the fact that it's more utilitarian than elegant, but I understand why that be a "no" for others. It has a small footprint too. One downside is that it's $104 for the kit, and the filters are an additional purchase which might not work for your budget. Plus side (at least for me) is that these filters are easy to get preordered to my local home improvement store.

if you ever feel like making your own air filter, check our r/crboxes for some inspiration. I have an coway airmega, a 6 fan cr box from NorthBox, a levoit mini, and one of the tiny ikea air filters. every room gets a different size and type of air filter according to the needs of that room.

Make your own "brisk box" from CleanAirKits. I do 12x12x1 boxes and I think I've gotten the price of the fan lid to about $80 DIY. 2 of those would be better than half the HEPAs in your budget. More so than just a filter, you should have a doffing process. E.g. Figure out your air volume, CADR (clean air delivery rate) and then you will have an ACH (air changes per hour). This lets you make informed decisions about how much filtration you buy and how safe that filtration makes you feel. I aim for 10-12 ACH and the recommendation I see most often is 12.

Check out cleanairkits.com. Their luggables look sharp and fit the criteria.  But they have slightly louder fans than their Bris box design the bros box isn’t as attractive. No other manufacturer will move the same amount of air at the decibel of these units.  But there is no speed setting, they’re just quiet. Every other purifier will clean less air or be louder and you’ll have to turn down the fan speed.

You need a couple corsi rosenthal boxes. Each one will run you about $90 in today's prices. They perform as well as a $1000 air purifier for 1/11th the price. r/CRBoxes can help. [https://youtu.be/hIuH-2naozI?si=xNUdt\_djOjXdJKja](https://youtu.be/hIuH-2naozI?si=xNUdt_djOjXdJKja)

Unfortunately that website has been completely taken over by affiliate link BS. 95% of air purifiers sold online are complete garbage. Have tried many over the last 15 years due to asthma and allergies. The only cost effective solution I found that actually works (have an air things air quality monitor so I can tell by turning on and off air purifiers) is a box using home furnace fan filters. I got one from clean air kits that uses computer fans and it's super quiet so you can sleep with it on. Mine is 4x 20*25" filters. You can make your own with box fans but they will be crazy loud. The 4 fan one is good for a small room. https://www.cleanairkits.com/?ref=ANNALE&gad_source=1&gad_campaignid=22709004639&gbraid=0AAAAA_ODbriF_jyz8Gjm983QOPyONyoIt&gclid=CjwKCAjwt-_FBhBzEiwA7QEqyI5KZ5R9_7eGZZIs3i8JuZzTyN3fsBU8lDCdZe9VxwvN-gMl4hPouhoCCpMQAvD_BwE And you don't need the most expensive filters either, in fact they work better with the mid range ratings as they have way more airflow. Mine are 10s or 11s I think...