B&H currently has the "old" 24mm Hasselblad HCD 24mm (1/800th shutter) for $6k (they had a used one for $4500 for awhile which has been sold), the newer one with 1/2000th sync is a little over $7k. The Leica S is ~$8800 at B&H, as is the Rodenstock (without lens mount). Pentax discontinued the 25mm AFAIK but a couple used copies have popped up lately for ~$4k. (all prices USD).
The currently announced XCD lenses for the X1D are $2295 and $2695, pretty far off from the $3500-4000 range cited above. Affordability is relative and subjective obviously. As ultra-wides tend to be more expensive than their other WA counterparts, I'd expect the price of a <30mm XCD to be somewhere between the current XCD lenses but less than the current 1/800th shutter 24mm HCD, which is currently the cheapest currently-available MF ultra-wide (AFAIK - ignoring the Pentax 28-45mm @ $5k new) - this would make it more expensive than the current offerings while still being affordable compared to it's other ultra-wide counterparts. Perhaps sticker shock for those entering MF but "cheap" for those with IQ3 100mp/rodenstock tech combos or other existing MF setups. I'm hoping that pricing of future XCD lenses stays in line with the current 45mm and 90mm prices, although I expect an ultra-wide and zooms to cost more.