Amazon has the Raleigh RX24 cyclocross bike for $304+tax. Regular/Full price is $649. Free prime shipping or slow boat shipping if you don’t have it. Hard to find a real kids CX bike this cheap unless you are looking at used.
Good review here . Seems like the biggest problem is the odd sized rims which limit future tire choices.
Picked one up for my son last night at $313 then refreshed and price dropped to $307. Now a couple bucks cheaper so they might be clearing them out and dropping the price even more.