Welcome. We don't know what year Frazer you saw in the car show, but since you have been doing some research, you can see that the so-called "slab sides" were made from 1947 to 1950. 1951's were essentially the same but with modifications to the carry over body.
The forum is helpful, but it does not always generate a lot of topical interest. I think the suggestion to become a member and get the newsletter is sound advice. There are a lot of KF guys that are not on this forum, probably 99% of the club, so I would post there a WANTED ad and see if someone has a 47-51 Frazer.
I am not a fan of the 1947-48's. They are OK, but need to be very nice originals or restored to really "pop". I love the 49's, but have not seen one for sale in over a year, in any condition. In fact, I have never seen a 49 Manhattan for sale in "nice driver" condition in the 3 years I have been interested in KF products.
Prices are all over the map. 2 years ago a low mileage 47 Manhattan from KS was on here for $1500 or so that needed "gone through" but was low mileage and could have been enjoyed as is rather then emptying your pockets for a restoration.
On the other hand, many Frazer owners have unrealistic expectations of what their cars are worth and virtually everyone is overpriced.
Maybe others will comment on yout topic, but the search may take awhile on the Internet, so I would cut to the chase, join the club and even before I got started I would send in a WANTED ad with my money and application. Club members have a few Frazers, so reach out that way for a quicker result.