Scroll costs:
Scrolls are sold at the Alchemist's shop.

Cantrip 25gp
1st lvl 50gp for scrolls
2nd lvl 100gp
3rd lvl 250gp
4th lvl 500gp
5th lvl 1250gp
6th lvl 3000gp
7th lvl 8000gp
8th lvl 20000gp
9th lvl 54000gp

If the spell requires a material, you must also have that to cast the spell or learn it.

To learn the spell:
For each level it takes a day per roll, you must either hit max roll or spend the number of days equal to the dice number. So for Level 1 you would only need to roll 1d4 4 times, and take 4 8-hour periods to learn max but might get lucky on the first day. Cantrips just require the scroll and a day. The scroll is used up only when the spell is learned, you must cast the spell once using the scroll once you learn it so be mindful of where you cast it.

Cantrip 8 hours, no roll.
1st level time is 1d4
2nd 1d6
3rd-5th 1d8
6th 1d10
7th-8th 1d12
9th 1d20

You cannot learn a spell from a tomb unless you yourself have a spellbook. Some do, some don't. In that case, you can copy a spell into your book and you will learn that by next level. Yulya has a book but she already has access to all the spells she'd ever need or have access to.

Ashley doesn't have a book but if she bought one she could utilize this mechanic. The time to copy a spell is 8 hours per level and costs 50gp for "special ink".