If you don't feel comfortable buying the coin then don't buy it. Another one might come along at some point but to know that no others have been sold on ebay for over 2 years leads me to think you might have to wait awhile for another one to show up. Pre 1967 specimens are in demand and I see them all going for 2-4+ times book value....even common ones like 1937's. For example, try finding a 1937 SP penny at the moment. None of the big dealers have listed any on their websites for 3+ years and ebay is the same. And yet Coinsandcanada lists a SP66 for $268. I'd gladly pay 2x that amount.
There have been no sales on eBay of 1948 SP66's in 2021 or 2022. Also, the prices you guys are quoting are from coinsandcanada so we dont know who graded them. For example if they were graded by NGC then they would be priced considerably lower than a coin graded by ICCS.
This is a heavily circulated dime and is nothing out of the ordinary. Due to its extreme wear, its value is based on the silver content which is about $2.20CAD at the moment. An easy way to determine that this is wear is to also look at the word "CENTS" which is also heavily worn to the point of being somewhat illegible.
It looks like the website for http://www.CNGCcoins.ca has been taken down but their misattributed/misgraded coins are being sold by West Edmonton Coin + Stamp and Pirates Cove Collectibles in Edmonton. Buyer beware!
I called the number on the webpage to chat with the owner. He insisted that the error on the 2021 bluenose dollar which is labeled as a PL rather than as a PF was a clerical error. I then pointed out the error on the 2002 Golden Jubilee silver dollar which appears at the bottom of the landing page that is also attributed as a PL coin rather than a PF coin. Again, he insisted it was a clerical error. He said he will fix these two errors and assured me that all 3rd party graders make clerical error's. I pointed out that there are 6 example coins on his website and two of them are attributed incorrectly which does not instill confidence in potential clients. He told me he has 7 'numismatic certificates' and insisted he's an expert. I asked if he was affiliated with NGC and he is not. He told me he is trademarked and will have CNGC coins listed in one of the upcoming Heritage Coin sales. Grading is a complicated subject since its opinion based. I've done several tests with ICCS over the years where I send in the same coins over and over again and they consistently get different grades, sometimes wildly different (eg from an MS-64, to an AU-55, and then back to an MS-64). No grading company is perfect and they need to start somewhere but based on the conversation I had with the owner, I didnt feel he was an expert in coins or grading.
This is a prooflike coin, probably PL-64 based on your pictures. It can be tricky to grade PL coins from photos due to the reflective surfaces. Its a common coin that sells for $16-$20 in this condition.