Pretty expensive, just checked Alibaba and there's some Proxmark clones for 62USD: https://www.alibaba.com/product-detail/Update-PM3-Proxmark-3...
edit: Aliexpress is even cheaper ($42) and is not in bulk (also, the hardware Proxmark design is open source): https://www.aliexpress.com/item/Newest-version-proxmark3-dev...