NASA have developed a low-cost rocket-fuel pump which has comparable performance to a turbopump at 80–90% lower cost.
Starting a turbopump-fed rocket engine is a complex process, requiring a careful synchronisation of many valves and subsystems.
In fact, Beal aerospace tried to avoid the issue entirely by building a huge pressure feed booster.
Their booster never flew, but the engineering behind it was sound and, if they had a low cost pump at their disposal, they might be competing against Boeing.
[2] The cycle is as follows: Rocket engines requires a tremendous amount of fuel at high pressure.
In this configuration there are often two pumps working in opposite cycles to ensure a constant flow of propellants to the engine.
This device has advantage over standard turbopumps in that the weight is about the same, the unit, engineering and test costs are less and the chance for catastrophic failure is lower.