Prices are more for plus sizes.  The 1x is $69
The bust is measured from underarm seam to underarm seam across the front.  Double to get the circumference. The length is measured straight down to the hem.
This top does run slightly small.
X-Small: Bust is 17.5" (35" around), length is 25"
Medium:  Bust is 18.5" (37" around), length is 25.5"
Large:  Bust is 20" (40" around), length is 26"
X-Large:  Bust is 21" (42" around), length is 26.5"
1X:  Bust is 23.5" (47 around), length is 27.5"