Your coin appears to be Mint State from the photographs, but why are you against purchasing certified coins? About 25 years ago I too was against slabs. I didn't think that you could enjoy your coins as well when they were in them, and I thought that they were a marketing gimmick for coin dealers to get investors, who could care less about coins, to buy coins.
My attitudes changed over time. The reasons were that certification provided assurances that the coin was genuine, and the coin was easier to sell when that time came. Among all coins I quickly decided that the "old" commemoratives were prime candidates for certification because they were quite often marketed to investors and more novice collectors.
There are counterfeit examples of the "old" commemorative coins on the market. The Spanish Trail is one of them. There are also many problem coins that are not in slabs for a reason. If you pay even a discounted price below the usual levels, you can get stuck. Why take the chance?
From what I can see, you coin appears to be a nice MS-63 that has probably been dipped. The price structure of the Spanish Trail commemorative supports the notion that you should buy the best coin that you can afford. Using Gray Sheet numbers the bid in MS-60 is $925. The prices go up very gradually as your progress to MS-65 which is $1,050. If you are going spend over $900 for coin, why not spend only $125 more an get an MS-65? I know these are wholesale numbers, but the retail amounts reflect the same thing. There is very little spread in the price until you get to MS-66 and 67. When I bought my Spanish Trail there was very little spread between MS-65 and 66, so I bought an MS-66.
I just toss this out there for your consideration. Here is my Spanish Trail, which is in a PCGS MS-66 green label holder.

