The star mark denotes early production (before Jan. 1918} Winchesters produced before Ordnance approved interchangeability between all 3 manufacturers was obtained. They were held back from issuance to European theater bound troops until approximately March 1918. This is more thoroughly explained in C.S Ferris book of the 1917.
The above auction rifle is unique in that it is a wonderful apparently unissued early Winchester originally from the Brophy collection. I suspect that drove the price premium.