I can't really help you on the price issue since I bought my Doughboy almost 6 years ago and it is a different model. We also did our own install because I wasn't willing to pay for the mileage and time out to my house 50 miles from the dealer. I do know I didn't pay separately for the liner.

Patterns aside you want to check out the differences in the liner thickness. I'm assuming with the price difference one is thicker than the other. Generally, the thicker the better...