Winchester had a whole lineup of blowback operated semiautomatic rifles in the early 20th century. The 1903 .22 Auto, 1905 .32 and .35, 1907 .351, 1910 .401, and model 63 .22 long rifle. The '07 and 63 lasted until about 1958. They are all good solid blue steel and walnut rifles of the period, of interesting design and manufacture; BUT their ammo is long obsolete.
I would think $300 to be a good price for a .351 but only if you had a large ammo budget to find old stock, buy custom made; or are an experienced handloader.