Gee, I've never had a problem getting coins in Europe. In fact, I've had quite the opposite problem, I accumulate too many coins. But then, I travel mostly in Germany, and there, cash is more commonly used. Since I'm not familiar with the coins, I tend to give out notes instead of figuring out what coins to give out, and I get back more coins. Pretty soon I'm carrying around five pounds of coins.
And the euro coins are so easy to understand. They're based on 1, 2, 5. Small copper coins for 1, 2, and 5 euro cent, 10, 20, and 50 brass (light brown) coins, and 1 and 2 euro coins with with brass or silver centers. Actually restaurants tend to round everything to the nearest 10 cent, so unless you go to grocery stores, you might not ever see the 1, 2, and 5 cent coins.
But the solution I finally found was to hold the coins in my curled hand, like a roll of coins, so I could see the edges. The 1 and 5, despite being very small, both have smooth edges, but the size difference is obvious. The 2 has a circumferential groove around the edge; almost looks like two thin coins stuck together.
The 10 and 50 have continuous notches, but the 50 is noticeably bigger. The 20 only has only a few, 7, notches spread out around the circumference.
Lastly, the two euro coin has continuous fine milling around the edge; the one euro coin has intermittent fine milling.
The 2 euro coin and the 50 cent coin are almost the same size and could be confused, but the 50 cent coin has those continuous big notches around the edge.
I have some euro coins at home, brought back from a recent trip. If you were in Denver, I would just suggest you come out to one of our monthly meetings, and I would sell you some. But I've never heard of a San Diego group.