Will HDI be affordable any time soon?

[TimCambridge]

I would expect that a capital-intensive laser drilling line is a plausible investment for one of the big board houses, but I haven't seen HDI prices moving down.

Should I keep looking?

[Psi]

Laser drilling on standard PCBs will probably happen before full HDI boards get cheaper.

There's a lot of benefits from getting 0.1mm via's on a normal spec'ed PCB.
It's probably not that difficult to upgrade an existing 4/4mil PCB fab line (maybe even 5/5) to include a laser drill stage.

[TimCambridge]

Laser drilling on standard PCBs will probably happen before full HDI boards get cheaper.

Would that be blind drilling between an (outer) layer 1 and copper on layer 2? That can be done after layer bonding; it sounds like an economical solution for the manufacturer and it would be terrific for simplifying layout. Perhaps it's available already in some corner of the market.

[Psi]

i was just meaning really tiny vias. 
but yes, maybe buried/blind vias too, within some rules.
It would have to make sense given how they already assemble the substrate layers.