Once you identify the pump correctly and if you don't have a book, and can't get an accurate recounting from a member here, use the internet and find what prices have been realized in today's market. ((FYI, nicely restored ~ $2500, so figure on deducting for restoration and missing parts, so estimates I've seen given up to this message are in the ballpark)).
BTW, Books are great for values at a specific point in time based on a specific author's opinion of value. The longer the time period between when the book was published and the current date the less weight those previous values have in determining current values. If the prices realized in recent auctions are combined with the book values a range can be adjusted.
I have to point out that one of the longest running series of price guides, Kovels, constantly revises their quotes based on new data and their website indicates the year of the value at auction. Likewise, websites like Liveauctioneers and Proxibid have similar date information and cover a wide range of sales. The caveat on auction sales is whether the auction was well attended, a specialized auction, and whether it is known to specialize in that particular type of item.
Since I deal in toys too I can tell you I have plenty of toy guides whose values are totally unrealistic in the modern economy and the values will never be seen again. Some toys have outlived the main collector market, while others were only fad valuations.
I think owning the books is great for reference and identification, but I take any valuations with a grain of salt.
Checkout my items for sale on Pauls Picks on Facebook.
Collecting anything keeps you young at heart!