While the official retail price of a D&D 4th Edition Dungeon Master's Kit is $39.99, you can get it from Amazon for under $30, and that is good value for money. You get a big box with a paperback which basically corresponds to a Dungeon Master's Guide, plus 2 booklets with an excellent adventure in 2 parts, 2 poster maps, and 3 sheets of tokens for monsters and players. As an "play right out of the box" experience after having started with the Red Box, this is pretty much spot on.
The only problem I have with the Dungeon Master's Kit is that 2 poster maps isn't enough, although they are printed on both sides. The provided adventures simply have more locations than that. And that leads to strange results, like you having a poster map for one half of a keep, but not for the other half. You can then hand-draw the other half on a dry-erase battle map, but the contrast will be jarring. Or you need to make your own battle maps. I found one source for .pdf maps for this adventure, I just need to find out how to print a pdf file enlarged over several sheets of paper. I would like to have something looking like this, but besides not being skilled enough for such a build, I have the impression that it takes ten times as long to build such a keep than you spend playing the adventure in it. I'm not even sure the 3D build is the most practical to play D&D on.
I am currently preparing a different adventure, but the fundamental problem remains the same: The adventure has far more locations than provided on poster maps. I want more poster maps! In the adventure I'm preparing, the general map of the dungeon is only provided in small in the adventure booklet. I tried using Dungeon Tiles for the corridors of the dungeon, but found that this doesn't work all that well. You spend too much time looking for the next tile, there is a strong risk of the dungeon coming undone during play, and if you want to stop the play session and continue another day it becomes tedious. The only advantage is that you can show the players just the part of the dungeon they can see, while a printed map risks showing more. I ended up designing and printing two battle maps for the same part of the dungeon, one showing the view when first entered, then other once fully explored.
Right now my best solution is still drawing simple dungeon corridors on a dry erase blank square map, and making battle maps for the fights on my computer using Campaign Cartographer 3 / Dungeon Designer 3. Those battle maps I then print out on regular paper and tape it together to form larger maps. That isn't quite as pretty as the poster maps, and for some maps I need to reduce the scale a bit from 1" squares to 2 cm squares to fit on a reasonable number of sheets. But unless WotC provides more poster maps with their adventures, that is the best I can do.