I can see the Tacoma being ~$10k more, but a Colorado? They discount those pretty heavily. I would expect the final price to come out around what you pay for a Frontier, or maybe even cheaper.
Not sure who told you they discount the Colorado, a fully loaded Z71 Colorado Crew Cab diesel short bed is $45K, take it or leave it priced. The new ZR2 Colorado's are expected to be $50K.
Local Napa auto talk show on Sat. mornings, the one host does vehicles tests as well, in his opinion, the Frontier is the best of the bunch, it's the cheapest, and quite frankly the most underrated, BUT, you have to be willing to overlook it's also more "plastic" on the inside. Expo Portal via their FB page did a long term test on the Colorado, they hyped it pretty good, before buying my Frontier I looked at them, no thanks. Highest price, smallest platform, least interior space, most unproven platform. In theory, the Tacoma and Frontier are at least based on a world wide platform.
I currently have 40K on my '15 Frontier, warranty items: paint (bumper paint began peeling), XM will occasionally tell me the antenna is unplugged, they check it, it's fine, a glitch. Replaced the front brakes at 36K.