I'll second what u/mhledwards recommends above - except I already had some standard card sleeves ahead of time, so I went with this smaller order of the Dephia sleeves for the minis. They're great, (nice and grippy), and I'll definitely be purchasing more for future games.

These are the Dephia Sleeves I used and here is what is currently being sold and here. I'm not a big stickler for "quality" of sleeves but more so bang for my buck. The Dephia was hard to beat but official sleeves (with the correct number), seem tempting.

If you are looking for cheap. Then these or these. The second are for Gloomhaven, which obviously would give you a terrible amount of extras.