Shouldn't be hard to grab one close to $19k OTD depending on how taxes and fees work in your state. As for the one ad $18.2, kind of doubtful that an OTD offer of $17.5 would be accepted. There's no better deal on the planet right now than a base V6. Anything. With a starting price in the 17's is a no brainer.
I looked at used Mini's too before pulling the trigger on my Mustang. Fun car, but scan the forums about service issues and you might change your mind, especially if you're on a budget. Keep in mind they're essentially a BMW. Parts and service are priced accordingly.
2014 V6 Manual