The real reason why HEPA filters are so expensive is mainly due to psychology and marketing. We are willing to spend a lot of money to protect our health, and HEPA filters and air purifiers are a great way to do that. If the filter is dirty, the compressor will have to work harder, resulting in higher current and utility bills. If you have an unusual sized filter area, some online companies offer custom filters for those unique systems.
Once you know the size you need, there are still plenty of options. The air system will have to use more energy to push the airflow past the blockage. Nordic Pure MERV 12 filters come in many sizes, so you should be able to find one that fits the return vent opening. Compared to basic filters, medium-efficiency MERV filters such as the Nordic Pure MERV 12 can reduce airborne dust, mold spores, pollen and even smoke, which can help alleviate respiratory ailments.
Washable filters can be cleaned more often if you want to keep it spotless, and don't always throw them in the landfill. Electrostatic filters capture smaller particles than a standard washable filter and are completely reusable. If you or your family have respiratory problems, they could be improved by switching to a filter with a higher MERV rating. Filters don't last forever, especially those with high MERV values that absorb and trap a large amount of contaminants in the air.
Filters become dirty over time and layers of dirt and debris soon cover the holes between the woven air filter mesh. MERV stands for Minimum Efficiency Report Value and is a measure of how well a filter removes particles from the air.