Costs for VFD vs Controllers

You will only get price differences by ringing the equipment suppliers directly, Boss, because no-one here is going to do the leg work for you.

As Crabtree said - you got to check. I have seen it both ways. About 2 years ago, we built a panel for an end user with pre-specified soft starts and just to quell my own curiosity, I compared the cost to a top end VFD from the same manufacturer and the VFD was cheaper. The other day, I checked out a similar scenario for a panel I was designing where the only use of the VFD was starting current limiting, as the motor runs full speed in use, and in that case the soft start was cheaper. The big difference between the 2 situations was the motor HP. The case where the VFD was cheaper was a larger HP motor. So, you have to check out the manufacturers prices to be sure. Note - in either case the cost difference was not very great.

You can put whatever inside-the-delta and reduce the requirements.

Not fully true, some softstarters (all those entry-level models without thyristor control of all 3 phases) cannot be used inside delta.

Inside delta is also a very good way to end with wiring mistakes as many electricians are not well aware of that wiring configuration.

Typing "Costs for VFD vs Controllers." into a search engine will give you the answer and save us the time.

Oh, that's the title of your thread. Quite clever of you, now, get to it!

All of that truth in the previous posts aside, it also depends greatly on the size involved. The smaller the motor power, the more likely it is that a VFD will cost the same or less. But in the area of 20-75HP they are close to the same, then at 100HP (75kW) and up, a VFD can cost 3-5 times more than a solid state soft starter. So knowing nothing else, it's impossible to predict.

But a very important distinction you must consider is starting torque. A solid state soft starter reduces the starting current by reducing the starting torque. So if your load needed the full motor torque to accelerate it before exceeding the thermal limits of the motor, a soft starter (or any means of reduced voltage starting) may not work. A VFD can accelerate any load that it can run, given enough time, without exceeding the FLC rating of the motor. This is the ONLY way to accomplish this. So sometimes, engineers specify VFDs because the limitations on available power are so severe that there is nothing else that will work, even though speed control is unnecessary.

Other issues to consider, the effect of a non-linear load on a generator, or other equipment on a power supply common to a unfiltered VFD or soft start.

This is the same guy with the dam gates, who probably wants (18) DOL starters with any method of keeping them all from energizing at once. Speed control is almost surely irrelevant.