I have also been shopping and researching wall tents and the Yakima looks like a nice one. I am looking for a 12 x 14 or a 14 x 16 with 5 foot walls. As far as the price of $450 for an 8 x 10? I suppose it depends on what it comes with. Is it a 10 oz. Sunforger treated? Is it Fire retardent treated? Does it come with a metal frame or the metal frame corners, screen door? sod cloth? stove jack? etc. If it's just the basic tent and frame it's probably in the ball park.
As far as the Yakima, I like what I see from their web site. I'm also looking at Rainier, Davis, and Bechtel wall tents. Post some pictures if you end up getting it and you get it set up! Are you getting a stove for it and if so what kind?