And the span would be?

The span is roughly 37'

The span is roughly 37'

I tend to use as many bearing walls in the basement as I can to save on costs. Most basement designs around here are finished, so I just work the floor plan walls to work with the bearing points. You will need to thicken the slab under the wall, however the cost of the concrete is minimal. I also try to select heavier ijoists or floor systems so they can span further and use less pieces. Depending on if they are drop beams or flush/inset beams, they also tend to complicate items such as plumbing, electrical, but mostly hvac systems (assuming the hvac is in the basement) and duct runs.
However for 37', unless you want less posts, you can easily get by with a couple posts and lvls. Longer spans are governed by deflection loads, and deflection is countered by depth of the member. So the longer the span, typically the deeper the member.

We have two load bearing walls that are not made of LVLs, they are just regular 2x6 studs. They builder told us that we didn't request an open concept and that is why he didn't use any steel beam but walls only. I think we are ripped off by him. It's our first time building a house and didn't know that we have to tell him specifically that we want open concept, we assumed that all basements are open concept with steel beam support. I just want to have an idea that by not using steel beam how much profit can he make.

As I said, most new basements around here are finished, so I use the bearing walls. It is cheaper around here, otherwise I would do wall infills. A thickened slab is acceptable for residential applications. A 2x6 wall typically sits on a roughly 2' wide, tappered about 8-12" thick with 2 #4 or #5 depending on loads. No forming or separate footer pour is required, especially since I also typically use SFPF.
And also, around here yet again, lvls are cheaper then steel. The only time steel is used is if we need to span a greater length while keeping the depth to a min.
Lose some future flexibility? Possibly, but then again, I only use bearing walls if the basement has a plan. If its left unfinished/undesigned, beams and posts it is.

neau-
you did not look at the plan to see walls and their locations? Are your construction docs showing walls or beams?
Pricing is too regional for anyone to give you a good ideal, especially without seeing the plan.

We converted a plan to remove a wall and replace with posts. We were not wanting to increase the costs much so we did not use steel. We have steel posts about 6 feet spaced - and that wasn't a significant cost increase but I don't remember the exact number.

Steel is more expensive than a wall for support but it isn't outrageous. We have some steel in our house - 2 beams I think and I recall about $1500. My uneducated guess is he saved about $750.

lZerarc, thank you for your input. So I guess if we want to replace one wall with steel beam and post, we are facing the risk of cracking our tiles on the floor above? I just thought the steel is more durable, wood is going to be affected more by moisture etc so our hardwood floor above may start making noise after a while because of this. But both of them are structurally sound, am I right?

"A thickened slab is acceptable for residential applications."

This depends on loading, and that depends on the actual structural design of the house.

If the roof framing uses trusses the middle wall loads may not be all the large, especially for a single story house.

Add a second story and the loading goes up.
Us a rafter framed roof to gain some space and the loads can go up again.

Smaller house engineering does not translate to larger house engineering all that well.
A lot of assumptions become invalid.

Because with a bearing wall, you're dealing with additional framing costs, wall covering costs, HVAC ducting and electrical, (which most people don't think about) the overall costs of the two are pretty close up to a point. That point is when you need a crane to come in and set the beams because muscle power isn't going to do it. You can usually get enough guys to handle a 20' or even 25' foot beam, but an almost 40' will need a crane to do this safely. So you might be talking 2-5K more to use the steel at that point?

"So you might be talking 2-5K more to use the steel at that point?"

It depends on how common it is in your area and local costs.

I can get a crane for a house beam for about $250 an hour, total charge including drive time of around $750.

Sometimes even less from the company I usually use if they have another job in the area.

Even how close you can park the crane to the house matters.

I don't remember ever seeing an interior bearing wall in a basement except where the basement was expanded for an addition. There's no reason for a span to be 37' clear. If you are willing to have a wall along that line, there should be no reason to avoid having posts at 10 ft. intervals instead. I would guess that bearing walls would be considerably more expensive than steel posts and LVL beams.