Csonka air purifiers "clean" the air by producing ozone. The will not eliminate smoke from the room. They are meant to be used after you are done smoking to help eliminate the residual odors. Ozone and live animals(including people) do not mix.
http://www.epa.gov/iaq/pubs/ozonegen.html
Ventilation is the cheapest way of getting rid of smoke. The amount of ventilation you will need depends on the cubic footage of the room. I am not sure how you plan on installing standard bathroom fans in a sun room. Most bathroom fans are meant to be installed indoors and vented through the attic. They are not sealed units, so unless you have a crawlspace above the sun room, I am not sure they would be practical. An inline ventilation fan vented through the crawlspace would be a better choice. A commercial smoke eater is a good but expensive alternative and does require maintenance.
