Hi andulolika hope you're doing well.
I think for that kind of items (specific for a country) here in bitcointalk "general" collectibles section there is not much interest. Try on Local Spanish board maybe, you can hope there is a collector ....
However best option is to sell directly in a exhibition to some collector or try with ebay/del campe.
I have not idea about the value of such type of coins... if these are valued more of 500/1000 euro best option is an auction house (cons ---> higher fees and expenses) since they provide guarantee for the product.
The "pro" is that you will have the opportunity to sell quickly probably at the best rate possible with minimum effort.
Of course lets wait other ideas/suggestion

Doing well thanks and I expect same of you!
Cheapest i found them on the internet was 30 eur, can go higher, 45 and such, however given amount of silver which is roughly 28 eur at this moment and that that site had only two pieces left, i do find them a bit more valuable.
I do find joy in getting crypto for stuff, perhaps i will try the spanish forum, I don't have too many sets either but as collector i do like sharing doubles.