@Chrysny413 I overpaid for a few bars when I first started and also bought some stuff I didn't really want but, discounting that learning curve, it all comes down to how much I want it, how rare it is/how likely another is to come along, and, of course, what the market value is vs the price asked. Like a lot of guys, I have a wish list and a focus for my collection. I've found all the low hanging fruit on my list (and, thankfully, much of the higher fruit too) so now, when something I'm still after does appear, I tend to pay what it takes (within a level of reason).
Best way to learn pricing is simply to monitor sale sites (here, FB, and eBay... understanding eBay prices tend to be highest but you are also most protected). I also pay attention to what parts sell for too, so I know how likely I would be able to get my money back, and hopefully make a profit, if needed.
But most Dutchies speak English, no worries 
