Basic info about script is available here:
https://www.ufopaedia.org/index.php?title=Script_(OpenXcom)
For functionality, yes, you can return arbitrary price, this mean disable default scaling, add custom scalling is possible too.
Scripts hooks itself expose:
`cost_current` -> current cost, after difficulty coefficient and possible change by other scripts hooks
`cost_base` -> original cost from item ruleset
`difficualty_coefficient` -> difficulty multiplier,
to have always control over default behavior.
[ps]
I see I make typo in `difficualty_coefficient`, I probaby soon push new version that will fix it as there is not lot of mods that depend on this.