Ryanair : 1st bag is around $10, 2nd bag is around $30
Easyjet also charge for bags

But this is an old list and I replied to it a few weeks ago with examples for all & worse from Ryanair - except for animals & airmiles which Ryanair don't allow

If you want to be appalled then read the full list of Ryanair charges

Oh - they don't do refunds if the price goes down, but few businesses, let alone airlines, do so once you leave the Socialist Paradise of America