@Edent Sorry for straying a bit from the actual question but I'd participate without compensation. Also if you insist on money changing owner how about having an option to designate a donation instead of personally receiving compensation?
If those are somehow not compatible with the procedure excuse my disruption.

@kraftner donating to charity becomes a bit complex tax wise - especially if the charity doesn't have a presence in the UK.

As I'm receiving money to run this, I think it's only fair I compensate participants for their time.

@Edent Does GoG have vouchers?

@Edent Oh sure, I never meant it wouldn't be fair to compensate it. In fact I think it is great and the right thing to do since obviously not everyone has the privilege to offer an hour of their time for free. And I of course didn't think about the complications of tax.
So, sorry for the noise, I just voted.

@Edent guessing something electronic to keep your logistics reasonable? How about https://www.nationalbooktokens.com/ (covers £ and €) which would cover physical books (and maybe some eBooks options?)

@imikotoba @Edent Yes, I would prefer a National Book Token to a Kobo one but it only works in the UK and Ireland.

@imikotoba @Edent But seeing now that Kobo sells DRM-free eBooks from Tor Publishing and "standard" Adobe DRM from other publishers, so I don't need one of their e-readers, Kobo also looks good.

@Edent een kadobon, maar let op geldigheidsduur: https://blog.gifty.nl/cadeaubonnen-wat-je-moet-weten-over-geldigheid-en-vervaldatum/

@wiert I don't really understand what you're trying to say, sorry. It is up to a recipient if they don't want to spend it in time.

@Edent Amazon voucher might have the widest appeal, unless you prefer not to support that company

@ogeer @Edent Ah, guess “National” was a clue and their Euro support is limited to serving (Northen) Ireland? I didn’t check that, sorry.

@Edent sorry, thought you were Dutch. People are bad at remembering expiry dates, especially when they are years in the future. Luckily, there are still a few Dutch gift cards that don't expire.

@Edent Wouldn't it skew the demographics of people who volunteer to test if you pick one kind of voucher, instead of offering a selection?

@richardloxley @Edent I avoid buying from Amazon. Recently got done gift vouchers and as it has been so long since I last purchased through them I had to update the card and in doing so it ignored the gift card balance. So annoyed as by the time I noticed it was too late to change it.

@Edent the Office for National Statistics, when they do surveys, give you one of these vouchers -- https://www.pluxee.uk/products/evouchers/ -- which the recipient can then choose from a bunch of different stores and restaurants and such. I turned mine into an M&S one one time and had a lovely dinner
No idea whether you have to buy 10,000 at a time or something, mind, or whether it'd work for you, but I found it useful, and the ONS presumably (hopefully?) did at least some due diligence on them being OK

UK's Leading Gift Vouchers for Employees | Pluxee

Boost your reward and recognition strategy with cost-effective and inclusive eVouchers: Employee rewards that give your people access to an unparalleled choice of retailers.

(www.pluxee.uk)

@Edent if the participant is in the UK, I'd say Argos. They sell stuff which most people will have to buy at some point at prices which aren't stupidly priced, and have collection points almost everywhere

@Edent I voted books, but https://uk.bookshop.org/gift_cards rather than Kobo perhaps?