That might be a cheaper route. Tell them that you need to put the house on the market and you need them to move out by next week and will help them out by giving them $250 (or whatever you feel might entice them) and renting a moving truck for them. State it like you expect them to comply (after all, you're their uncle and it is your house). If they balk, then you're out nothing and you still can start an eviction process.