I think I MUST have mountains + that picture I linked AND make it all painted. The need to build a full on castle from all angles is low. I feel like having the façade, walls and towers is great. I can use my KS 1 to fill in the insides ( I think). The mountains are just a perfect addition to KS2.
think the battlements are so much nicer than the crenulations because of the extra play space.
Ok, that giant Gatehouse Facade can actually be made cheaper than I realized - I don't know why I didn't think about Cube Spacers before.
Before I get too far into it - Bullmag, how important to you is having the interior space of that facade playable?
If you don't care about interiors and just want the walls and tower tops, you can do that pretty cheaply and rock solid with just 2 packs of Cube Spacers ($70 total unpainted) added to your Gatehouse and basic Wall and Tower bits.
If you want the inside tower halves and the 4x6 inch space shown behind them in your pic playable, you can probably do it pretty well by adding 1x Square Tower and 2x Stone Advanced Builder ($203) to those cubes. Gets you some CBS to play with in builds.
Battlements are beautiful, but expensive on a budget and the price adds up quickly. Crenellations would be cheaper, but you could start with a Watchtower instead of plain tower levels and add on 1 Straight, 1 Corner, and 1 TransitionBattlements ($95 Unpainted) and have those 2 towers plus up to 10" of wall on both sides covered with Battlements.
Anyways, again - how important are playable interiors to you there? Let me know and I'll try to sketch out this build.