Sure, it's probably not as detailed as Forge World stuff. I bet they have their reasons to sell at the price point they do. But when I receive stuff like this (and the Alien Brain) which has barely no flash or seams visible it sure feels like Forge World is charging a bit too much.
Aaaaanyhow... The Feldkanone came with no assembly instructions, but there really wasnt any instructions needed. You just place the cannon on the carriage, slide the shield over and attach it on the carriage with two pegs on the backside of the shield.