Broadsword with a Bladesharp 2 matrix: Sword 50L + Bladesharp 2 150L (half price if from a cult) + Spell matrix POW cost 400L = 600L.
For POW crystals I've used the cost of MP and Spirit binding enchantments. MP enchantment: 200L you get on average 5.5 MPs, so the L/MP would be 36.4L. But since the crystals have the dual use of spirit binding too, and normal spirits have two abilities, a spirit binding enchantment would cost at least 400L. But you can't use a crystal for both purposes at the same time. For smaller crystals that wouldn't be of use for spirits, I've just used the MP enchantment cost, and for larger ones the minimum cost would be 400L.
There are no magic item shops around in my campaigns, except in some strange places like Pavis or Casino Town, but the characters can commission items between scenarios.