$450 might be a bit high, but look at the PBC prices, $799. I get there is more stuff in them.
I just built one and I'm sitting just at parts, $180 into the thing. Now if I were to take that up a notch to being a full custom cooker, powder coated and all that, that cost is going to go up as well.
I've also not charged myself for my time and labor! See the attached image:
The one on the right is the one I just built. here are the basics, Barrel $15, Tel Tru $45.20, rack was $18, coal rack was $10 then all the rest of the hardware.
If I were to build them, just standard, no paint or anything $250-$300 wouldn't be a bad price point. They are ten times better than any COS you can get at a box store for the same price. I know, I just got a Char Griller at Lowes for total of $300 and I'm going to smoke more on my UDS' than it lol