THIS IS NOT A REPOST: This is a different model. The other posts that have been here or on other sites are for the MS-401 which is a diaphragm sprayer. Different model, different retail price, different sale price.
This is the Piston Pump Echo 4 Gallon MS-402 Backpack sprayer.
On clearance for $25.03 down from $99.97 at Home Depot.
Clearance price is not shown online or the mobile app, but brickseek shows them on clearance with the quantity.
Remaining stock and price could vary by store, but there are several of this model as well as the other diaphragm model that is on clearance as well.