I know what you mean!!! I've probably got over £600 worth of filters, it's easily done! Landscape photography isn't cheap, a decent tripod and set of filters is easily £1000, but IMO too many people get sucked into wide is best for landscape, before going Fuji I had a crop Canon with a Sigma 10-20, I went through my WA photos and found that a lot were shot at 14mm (21mm FF equivalent), so that really made my decision. It also means that I have a nice two lens lightweight setup, 14mm and 18-55mm which share the same filter ring and hood.
Going back to Zeiss v Samyang, IMO unless you need the AF of the Zeiss, buy the Samyang (I did have one briefly, but felt that it was too wide - for me). You have to take a lot of care when shooting WA to ensure that there are no unwanted elements in the FOV.