I assume that Whippet sign is double-sided? You can do a search on liveauctioneers.com (sold results) to get an idea of the current auction market. Like Kevin says, you also have to factor in the BP. Based on what I see, I would value your sign around $500-700, given the condition. Here's the link to recent auction sales (sorted by price) on liveauctioneers that you can copy/paste into your browser:

https://www.liveauctioneers.com/search?parameters=%7B%22keyword%22%3A%22whippet%20sign%22%2C%22sort%22%3A%22-hammerPrice%22%2C%22status%22%3A%22archive%22%2C%22page%22%3A1%7D

Joe