Lenovo's Smart Display has been discounted quite often as of late, but the deals are often restricted to members of a certain store or are only available in limited quantities. Several retailers are currently offering the 10" model for $149.99 and the 8" model for $99.99, meaning that both have had their prices cut by $100.
There are really only two differences between the 8" and 10" model: screen and material. The 8" model has a 1280x800 display, whereas the 10" has a 1920x1200 panel. If you plan on watching videos often, you may want to spring for the 10" model. It's also worth noting that the 10" model has a bamboo rear panel, while the 8" just has some white plastic.
B&H, Lenovo, and Walmart are all offering the 8" and 10" models at these prices, so you can have your pick at which store to buy from. Walmart is probably the best bet for most given that it has brick-and-mortar locations and it offers free two-day shipping, but if you live in a state that B&H doesn't charge tax in, that might be a good way to go as well. B&H also offers free expedited shipping. Lenovo also offers free shipping, but its standard speed is slower than the other two stores.