Carrying forward the status quo from 1923 and 1927, only the San Francisco mint struck Walking Liberty half dollars in 1928. Fewer halves were made in 1928 than in any of the two preceding years, though prices would not reflect that fact, at least for examples in the lower grades. In 1928, 1,940,000 Walking Liberty halves were struck, and most assuredly a small fraction of those survive to this day, thanks to meltings and loss to time and its harsh elements.
Prices for a 1928-S Walking Liberty half dollar in a grade of Good-4 are under $15, though climb to around $200 for the date in a nice grade of XF-40. The steep jump in prices for a 1928-S between the lower grades and the upper grades is to be expected among all early Walking Liberty halves, which were saved in scant numbers among the better grades.
There is one little caveat for die-hard Walking Liberty aficionados to take note of for 1928-S Walking halves, and that is the fact that both large and small mintmark varieties exist for this issue. There is basically no difference in price between either the large- or small-mintmark pieces, but it is a point of interest for those who want to add a little spice to their Walking Liberty half dollar collections.