Purchasing a Scroll of Ray of Enfeeblement (1st) - 25gp
This gives her 9 1st spells to copy. To master a 1st level spell she needs to make a DC 16 spellcraft check but her current bonus is only +14.
Detect Undead wasn't successful but she does understand and copy eight. Copying costs is 10gp per spell so that's 80gp for a total spend of 105gp
(Please add all the first level scrolls except Detect Undead to her book)
Rolls:
Melody Capella
(Spellcraft):
16
= 1d20 [2] + 14
— Unseen Servent
Melody Capella
(Spellcraft):
24
= 1d20 [10] + 14
— Shield
Melody Capella
(Spellcraft):
27
= 1d20 [13] + 14
— Chill Touch
Melody Capella
(Spellcraft):
29
= 1d20 [15] + 14
— Colour Spray
Melody Capella
(Spellcraft):
15
= 1d20 [1] + 14
— Detect Undead
Melody Capella
(Spellcraft):
33
= 1d20 [19] + 14
— Endure Elements
Melody Capella
(Spellcraft):
17
= 1d20 [3] + 14
— Feather Fall
Melody Capella
(Spellcraft):
29
= 1d20 [15] + 14
— Floating Disk
Melody Capella
(Spellcraft):
17
= 1d20 [3] + 14
— Ray of Enfeeblement