It depends on the coin's condition. Normally the mint mark is also important, but 1945 halves from all 3 mints are roughly equally available so all have similar prices. If it's well-circulated, your coin would retail for about $6. If it shows hardly any wear at all, it might sell for $10-12. Other conditions would fit in between. The Walking Liberty half has always been one of my favorites - nearly as elegant as the St. Gaudens gold double eagle, and a lot more affordable.