In lieu of your trial to spend 20 neptunium on an extra specialist, maybe you could consider a specialist that is like a "HR Manager" and allows for a small percentage time bonus on the next hire - say 5% / 10%, which would allow the player to gain access to their next specialist in about 0.9 / 1.8 hours quicker....

the goal of allowing players to buy specialists was to "take the bullseye off their forehead" in case they ended up in too strong a lead.

as far as specialists are concerned, we actually want to have fewer of them, not more of them, so we probably won't add this type of specialist.