I get all my stuff off of amazon. I just fill my wish list with stuff, then I wait for stuff to drop in price and pick up what ever's been discounted the most. Schneider was sitting at $155+ for the past half a year, but just recently dropped down to $80 range, so snagged one. Panzer has been pretty steady around $70-80, but he's been going up lately.
Are you set on the Markings Plus or would the OG release do? That one is a bit cheaper: https://www.amazon.co.jp/-/en/Kotobukiya-Zoids-RZ-041-Panzer-Plastic/dp/B007CUHBYY/ref=sr_1_21?dchild=1&keywords=zoids%2Bhmm&qid=1601069791&sr=8-21&th=1
The Liger Zero and its CAS variants are extremely popular. Koto has done a number of reprints on them. With the Jager armor coming out soon, they're almost guaranteed to do an armor-only reprint of the other two. At the least you can grab yourself a base Zero and play the waiting game.
A bit over priced now but here it is.