Is there somewhere to buy used Latvian books in Riga?

I'm finally travelling in the Baltics and hoping to add to my collection of translations of a certain famous novel that I collect. As a booklover and as a person on a miniscule budget, I like to dig around in secondhand bookshops for them.

In Tallinn I found a good bookshop in the old town with used books, and one of the major new bookshops even had a used section. Also in the old central market there were people trying to sell junk including mostly old Russian books.

But here in Riga even though there's a few new bookshops around, I've only found one thrift shop with a book section, and one language bookshop with new and used books, plus some stalls in the underpasses near the station which I think only have Russian books. Nothing to compare with Tallinn. But Riga is also much bigger so it'd be easier to miss them here.

In particular, the central market here is very big, but has also been renovated. I couldn't find books there but may have missed them.

Maybe there's even some weekly or monthly flea market?