J.W.
We have the Oreck XL and it works very well. We sleep much better now that the allergens were cut down. It cost around 250 at Costco when they have it.
For about 1,000 you can get the same technology on a whole house level which is what we are in the process of doing. I used to have one for the house but my idiot of an ex threw out the collection units during our divorce. To replace them cost almost as much as the system so we are trying to find out exact costs and the improvements in technology.
The nice thing about these types of filters is there is no replacement filters you just clean it, dry it and then fire it up again. The initial cost is greater than those that use media type filters but in the long run are much cheaper and easier to maintain.