I think it's a great idea to choose hardware early in the process (we picked ours somewhere in the middle, which also worked out fine) because I was sort of astounded by how all-over-the-board the prices were. (I was also surprised at how we reacted to different pulls and latches, too---I sort of thought similar designs would be roughly equal, but the actual feel and operation made a huge difference in loving/hating different options, so I'm really glad we didn't skip ordering samples.)
Ours averaged $10/pull in the end, I think (which was actually a mix of *really* expensive latches and not-so-expensive pulls) so it was about $250 all told for a medium-sized kitchen (plus another $50 for hinges, but that was a choice we made since our cabinetmaker included the cost of concealed hinges in the cabinetry cost but we asked him to use exposed hinges instead, and therefore had to supply them). But that could have been far higher or far lower if we'd made different decisions on exactly which to choose! (Also, because we picked them early, I waited for the store where we were getting them to have a sale and then bought them all at once, so it's very handy to know what you want in advance so you can buy on your own time.)
Q