Without information on how large an area you are having done, and the general area in which you live, it will be difficult for anyone to give you any information.

The reason that we need to know where you live is that costs vary dramatically between different parts of the US. A reasonable price in San Francisco might be outrageous in rural Indiana (for example!)

Good point! just updated!

The underlayment and leveling is crucial in a basement if you're using anything other than carpet. If you lay ceramic or porcelain tile on a floor that isn't level you're going to have issues with uneveness and over time, cracking. LVP is more forgiving of variations in the floor, but still needs to have the low spots brought up to a tolerance (the manufacturer should state the tolerance). I can pretty much guarantee you that your basement floor isn't level as builders don't concern themselves with that when they're pouring - unless it's part of the build specification - and the average home is not like that.

Unless you're in an area where there is only one option, get another estimate on the LVP to make sure the first one is reasonable. But to @kempek01's point, the cost will vary depending on where you are and how many square feet you're covering.