We just did the car rental and drive to Emerald Lake last week - we loved it, despite the lack of bear sightings. We loved having the flexibility to stop when when wanted vs when a tour driver decided. And instead of waiting for 20 people at each stop, we could be quick when we wanted, or take more time as desired. I printed out the free pdf of Murray's Guide, which allowed me to read aloud what we were seeing as we drove along. My husband might wonder what [this] was as we were approaching, and the guide always had the answer. As suggested in the Guide, we stopped at Tutshi Sled Dog summer musher's camp and played with adorable 4 week and 8 week old puppies, and learned about mushing. We didn't take the sled ride that was on offer. The Guide also shares information on bathroom options along the drive (stop in Carcross) and gas stations in Skagway. Had we not already visited on our last trip, we'd have also stopped at the Gold Rush Cemetery and Lower Reid Falls on the way back into town. My only regret is forgetting to buy the recommended doughboy treat in Skayway.
We paid about $170 all in for our rental car, which included an extra $10 for having it dropped right at the dock for us, so we didn't have to walk into town to pick it up. We were also able to leave it at the dock and pop right back onto the ship with a couple of hours to spare. We spent about $40 on gas. We rented from Affordable Car Rental, which was less expensive than Avis. Booking online didn't work, but we emailed and got a quick response and finished the booking by phone.