Thanks, Sean. I'll have to inquire as to whether they offer hard gold over nickel for edge connectors. I know of a bunch of relatively low-cost PCB fabs, but they generally either don't offer hard gold, or only on large runs, or only for really big bucks. The actual cost of the gold on a hard gold edge connector is only a few dollars, which doesn't justify adding >$50/board on a short run, IMO, but that's what I've usually been quoted.
Note that "hard gold" is much different from electroless nickel immersion gold (ENIG), which is a much more commonly available surface finish that is used on an entire board surface, but NOT suitable for edge connectors. ENIG uses a very thin gold layer (about 0.1μm gold over 2μm nickel) that will wear off the the edge connectors in only a few insertions. Hard gold for edge connectors is typically 1-2 μm of gold over 3-6 μm of nickel.
