I'm in the assylum dungeion, and I've found nineteen coins for the shoe machine. Is there a twentieth coin to get a better pair of shoes?

Yep. If I'm not mistaken I think there are twenty-five, that I've found.

woops, i just found two more. They're all located within that one map, right? I've tested it out and SPOILER
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I've found that five get you boots of the north, ten is grounding, fifteen is speed, 20 is jester chain, but what do you get with 25? I'm considering taking the boots of speed, and just moving on, since those seem like the most useful items there. what do you guys suggest?

Spoiler
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There are only 21 tokens. Get the Boots of Speed and the Boots of the North.

Yes Mr.Dundee
there iz only 21 in the game unless u use cheats
p.s. do u kmow crocodlie dundee?

Black Paladin

If you have ToB installed, hold down the TAB key to highlight all the items and treasure niches. From memory, there are a couple of spots (containing tokens) that are easy to miss.

If you don't have ToB, but have the cheats enabled, pressing CTRL 4 has the same effect.