If you’re stuck with a lot of points before firelands patch hits on 28 Jun, here’s one good way to deplete them:
Buying heavenly shards with either 600 Justice Points (600 JP) or 600 Honor Points (600 HP) to ensure that your Justice + Valor is less than the cap and that your Honor + Conquest is less than the cap. But of course if it is very close then the dust is better as you would want to start off the next patch with points at the cap or as close to the cap as possible.
This is actually slightly more cost efficient than paying an extra 100 JP for a relic to disenchant into a shard. Most of the other options are not cost effective except for the Greater Celestial Essence which would vary from server to server. On my server the heavenly shard sells at a slightly better rate than the Celestial Essence.
Here the rate is about slightly more than 11 gold per 100 points. A hypnotic dust would only sell for 2-5 gold on my server.
With the next patch heavenly shards should bump slightly up in terms of price as people are more likely to disenchant relics for the purples into maelstrom combination, pushing down the price of maelstrom crystals although if there are many progression guilds on your server the demand for enchants will push maelstrom crystals up sharply too along with heavenly shards.
It is unlikely that the supply of heavenly shards will increase that dramatically as people would still need blue items as they enter heroics and people who have no need of heroics are still likely to steer away from LFG groups.