Family Tour of Krakow/Warsaw -not a traditional bus tour

Hello everyone. Has anyone every booked a tour for a group (in my case extended family approx. 7-12 or so people) to stay in Krakow in one of the large flats or houses with a private Polish guide? We live in the Philadelphia PA area. Cheap airfare/hotels etc. are available in Polish neighborhood, but it means going on a bus tour. We would prefer traveling with a solo guide that travels with us where we want to go when we want to go. Approximately 7-10 days. We would like our "home base" to be Krakow (tour Auschwitz for as long as we want, Wawel castle, etc.) Travel to Warsaw old town, etc. Is this possible without spending a premium amount of money? Are traditional bus tours the only option for us? Has anyone ever successfully done this for a "reasonable" price? Any suggestions, experiences, pitfalls to avoid, etc. you care to share would be most appreciated. Thank you. Donna