The sell value of this item is 40% of the total cost.
Compared to potions each charge is worth 49 gold (28 for health and 21 for mana) or 53.9 gold (30.8 for health and 23.1 for mana) when using the Alchemist mastery.
Assuming you eventually sell it, Crystalline Flask breaks even with regular potions once a champion consumes 4.22 charges. When only considering health, it pays off at 7.375 charges. When only considering mana it takes 9.86 charges. When using the Alchemist mastery the flask pays of at 3.84 charges considering both health and mana, or at 6.72 charges considering only health. Finally considering only mana the flask pays of at 8.96 charges.
Health regeneration speed is the same as a potion (10 health/s) while mana regeneration speed is a bit lower (5 MP/s vs. 6.7 MP/s)
Although many people might not compare this item to a combination of Faerie Charm and Rejuvenation Bead, it would take five minutes (180/.6) to get the same mana regen, and six minutes to get the same health regen (360/1) per set of 3 charges. Furthermore, unlike Faerie Charm and Rejuvenation Bead, which are absolutely useless while you have full or no health/mana, you can choose to use charges as long as you have them.