After a resurgence of steel frames about five years ago, it looks like the market has fallen off again. Dave Yates and Bob Jackson in the UK have gone (although Jackson's is going to re-open) and Argus Cycle's (along with most other builders) prices exclude all but the richest buyers, as does the super Italian offerings. Steve Goff is still in business, although how much longer he will keep going is anyone's guess, and lots of long-established shops have closed recently.
It seems to me that the type of enthusiast who build their own bike has almost disappeared, and that most riders now simply buy an off-the-shelf bike from the big manufacturers. This cannot be good news for Campagnolo who equip hardly any OEM bikes and rely on special builders for most of their sales, being the groupset of choice for those who dream of creating their dream bike. You cannot stand in the way of progress.