I haven't seen a Shapton or King 1K stone for under $50 but will take a link to the one you recommend.

The King K1000 usually goes for around $25-30 but is currently available for $20

https://smile.amazon.com/KING-Grain-Sharpening-Stone-Medium/dp/B0016VC46A/

The Shapton usually goes for $35-$45 on amazon but varies a lot and is currently higher. Wait a few days and it will be low again.

Both can also be found elsewhere routinely for similar or lower prices.