A challenging quandary to be in, for sure. $125 isn't going to "break the bank"; BUT, what are you getting for it??? I have looked for an authentic Lakefield paddle for years, and never seen one. About 6 or 7 years ago, I came across two reproduced full-size paddles bearing 'Lakefield' decals at an antique show. I was curious and tempted, but did not buy. The decals looked like fresh reprints and the paddles simply looked too new. I pressed the exhibitor for background. I was later informed that the two items (one light wood, the other dark) had recently been made, and that reproduced decals had been added. The two pieces were 'replicas', to put it politely; some might simply have said "fakes". In your case, I think you did the right (and safest) thing; here's why.
The original vertical, oval-shaped Lakefield decal from long ago, when the company operated under the name "The Lakefield Canoe Co. Ltd." showed a rather dark complexion Native wearing a colorful Chieftain's headress, in profile and looking to the viewer's left. The company name is above the Native in an encompassing gold band, while the geographic place name "Lakefield, Ont. Canada" is at the bottom. (See photo below.)
The decals on the paddles as seen in the photos above, posted by Paul Miller, show much the same Native Chieftain, although the company's operating name is now "Lakefield Boat & Manufacturing Co." The company went through about 7 different, but similar, names over the years. As Dick Persson has suggested, that particular style of operating name likely relates to the 1939-1942 era. Aside from the name change, the overall decal remains much the same.
By the time one gets to the mid-1960's, when the company was being operated by Jack Richardson and his associates (Rilco), the operating name had become "Lakefield Boats Limited." This can be seen in the photo of the revised decal (below), which is on one end of a double-bladed kayak paddle I have, that also has an accompanying "Richardson Aquacraft" decal on the other blade. Look very closely, however, and you will see a glaring typographical error that went completely overlooked when that batch of decals was printed - in the geographic place name at the bottom (below the Native figure), the town's name is spelled "Lakfield"; an "e" was left out between the "k" and the "f". And, it wasn't just one or two cases; that decal with its mistake got used many times over. Just when that printing occurred, I am not sure. The coloration in the decal also seems to have changed slightly.
Now, in the case of your 'find' (which the seller's tag purports to claim is from the 1950's), the decal looks new, pristine, later in time, but bears no spelling mistake. It does have the added bit of ribbon at the bottom, bearing the words "Registered Trade Mark", as does the mistake-bearing decal, but neither the very early example, nor that shown in Paul Miller's photos of the 1940 paddle. I believe the decal on the paddle you found in the antique shop is really a recent reprint, and one in which the copier corrected the spelling of the place name when making up the reproduction. I agree with your 'gut feeling' that the decal looks far too pristine to have the age claimed. I would offer the same thought about the paddle. I would have been reluctant to buy. It may well be the same piece I passed on 7 years ago, or a similar effort by the same repro artist.