If $$ is your big concern - then either skip the iPod or buy a very cheap substitute (some low storage mp3 player that perhaps holds a few hundred songs) or a CD player that also plays mp3's burned onto CD's.
However, if you can afford an iPod, I'd skip the mini-iPod and get the 20 GB or higher version. The price difference between a mini and a regular iPod is only about $50 - yet you get a LOT more storage room (and the size is comparable).
The U2-themed iPod is $50 more - if you want that extravagance, it's up to you.
However, as a person who has an iPod I can tell you that I LOVE IT!!
I too debated about getting one, but decided on doing so in December. I've used it virtually every day since. I use it when driving, when waiting in the airport, while at work, etc. I have not only tons of U2 songs on it (to satiate any U2 mood I'm in), but music that will cover all of my moods, from disco to rock to Sinatra to remixes. To me, it is well worth the $$.
A lot of the iPod extras can cost a fortune, however, for $12 you can get an iSkin (which I recommend) or for $30 a leather carrying case (which I currently use). You definitely want something to prevent scratches to the iPod.
If you only have a few hundred mp3's you know you'll listen to while in Europe, then perhaps the CD-mp3 player is better for you. However, if you have tons of music, then you will definitely love the iPod and realize what a great purchase it is.
Good luck on your decision and have fun in Europe!