Some old or very rare coins I have in capsules but as this system is very expensive, I collect the normal Euro-Coins in an album where 5 complete 1c-2€ sets or 35 2€-commemoratives fits on 1 page.
I prefer this also because it gives an easy overview about what's comlete and what's still missing.
When I got a silvercoin-collection some years ago which were kept uncapsuled in a box since the 1960/70s, I noticed that most of the coins were totally oxidated at the side which had contact to the ground of the box.
But well, that was silver, if you pick normal coins from circulation, this shouldn't cause any problems but if you collect all uncirculated pieces which were never touched with bare fingers, capsules are probably the very best way to keep their excellent condition.
If you need just 1 set from each country, it won't be a big financial problem I guess but if you look for each year and mintmark, it's to expensive, at least for me.
