What's a good price to pay

What do you think would be a good price to pay for a 2012 Prius v with an advanced technology package. It has 42,000 miles on the clock and is a one owner trade. It's a really nice clean car. If I can strike the right deal I might trade my 2012 Prius 3 with nav, leather, solar power sun roof and I have 58, 000 miles on mine. Also is there a big hit on gas mileage with the v model with bigger tires? . I respect all opinions. Thanks.