Memento Magica

Sorcerers, bards, and all spontaneous spellcasters of all sorts can benefit from a memento magica. A memento magica appears to be an amethyst cunningly cut into some draconic shape, often that of a dragon's scale. A memento magica is a great aid to spontaneous spellcasters such as sorcerers, bards, and favored souls, much as a pearl of power is to casters who prepare spells. Once per day on command, a memento magica enables its possessor to regain any one spell slot that she had previously used that day. The spell slot is available just as if a spell had not been cast. A memento magica can only recall a spell slot of the level it was created to hold. Different mementos magica exist for recalling one spell slot per day of each level from 1st through 9th.
Strong transmutation; CL 17th. Craft Wondrous Item, creator must be able to spontaneously cast spells of the spell level to be recalled; 750 gp, 60 XP, 2 days (1st); 3,000 gp, 240 XP, 6 days (2nd); 6,750 gp, 540 XP, 14 days (3rd); 12,000 gp, 960 XP, 24 days (4th); 18,750 gp, 1,500 XP, 38 days (5th); 27,000 gp, 2,160 XP, 54 days (6th); 36,750 gp, 2,940 XP, 74 days (7th); 48,000 gp, 3,840 XP, 96 days (8th); 60,750 gp, 4,860 XP, 122 days (9th). Weight: -; Price: 1,500 gp (1st); 6,000 gp (2nd); 13,500 gp (3rd); 24,000 gp (4th); 37,500 gp (5th), 54,000 gp (6th); 73,500 gp (7th); 96,000 gp (8th); 121,500 gp (9th).
Source: Races of the Dragon