We do this in my group, only we do a whole day, about 4 times a year. We use the community room at the fire station, or sometimes the community room in our PUD building. No fees, bring whatever you want to work on and snacks to share.
We also do our own retreats. We've used retreat centers in the past, but now are at a hotel where we get a great group discount. When we go shop-hopping, if we tell the shops that we're staying at the the hotel they give us a discount.