Thanks for the comments, Victor. I've been collecting for about 10 years now and on the ebay front I have to agree. I use to be able to pick up good campgates for around EUR30-50, the same for potin tetradrachms. Lately however, campgates on ebay are in the EUR60-120 range. I also agree that during the last few years I have started looking at more established auction houses as well and that might account for my bias. Another factor might be that as my collection grows, I start to think more about the quality or rarity of a coin and thus if something rare comes up, I notice it more.
But I guess as with any hobby, the longer you are in it, the more expensive the toys become :-D