From what I have seen on
ebay and other sites and one who is starting a silver proof collection set (I have 2018, 2019 and 2009 to start) you get more for them if they have the OGP and COA --- and on
ebay people actually auction the boxes and OGP packaging!
So as you do not have them and fortunately none of your coins have gotten a green film or cloudiness on them from the PVC in the holders I would prefer breaking them open and storing them as others have suggested.
As for what you paid - a very reasonable price. The 55' and 56' actually will get you more than $20 -- on average $50 - 60. After 1956 then prices drop for those with silver (until 70) to about 15 - 20. There are exceptions 1970 Proofs with small date command a higher price over $50 or more. But fomr 1971 the prices drop precipitiously - usually a few bucks UNLESS you have error coins. I had
inherited from my family a ton of 82 proof sets and what I was offered was just alittle above face value. I ended up breaking up the sets and cashing them in. Yes I could have made more money selling say the Kennedy halve 1982 proof and others but I had already spent much time researching and selling more valuable coins from the collection that I felt my time was more valuable than the effort required to make a profit.
If you are interested in silver proof sets as a collecting goal the ones from 2010 - 2018 have mintages about that of the proof sets from 1955 - 1960 and most have sold at or significantly above the original issue price when the US Mint sold them.
Here for example the 2014 silver p[roof set - running about $45- 50 at
ebay -
https://www.ebay.com/sch/i.html?_fr...c=0&LH_BIN=1