Do you want a BIFL model?

Most units are not built with a housing or motor or even a cord that will last a lifetime. A few exist that are built in the US and Canada, but these units are generally at the upper pricing spectrum. Most of these units, unlike the imported models, are also designed to impact volatile organic compounds (VOCs), and they have higher operational costs as a consequence of this.

If you are looking for a good purifier for a smaller bedroom, the Winix 5500-2 and Coway 1512 are both hard to beat, as they are around $150 on sale, have a decent amount of airflow, have reasonable filter replacement costs, and are reasonable with respect to energy usage and noise. If the room is over 400 square feet, you would want either a larger unit than the 5500-2 or 1512 or to consider two units if the bedroom is exceptionally large (or a much larger single unit). These are not BIFL products, however, even though they are reasonably well made. They will work against particulate matter (PM) - they will not have much impact on VOCs.