As someone who's grinding Ogrila rep at the moment, I say do the Big Simon, not the little ones.

Yes it costs 35 shards, and as mentioned above gives the buff for whole group which makes it a real time saver.

Also on the Big Simon you only need to go up to 6 colours to get the buff, on the smaller ones you need to go to 8.

Finally the Apexis Guardian that gets summoned at the end drops an Apexis Crystal and a level 70 green (guaranteed). When you get to revered with Ogrila, you can use the Apexis Crystal with 50 Apexis Shards to buy one of the level 70 blues from the Ogrla quartermaster, which you can then DE for a Large Prismatic Shard.

And don't worry about farming the Apexis Shards...you will be swimming in them by the time you get to revered (I have around 750 on each toon atm).

If you're looking for a way to make money there are 4 elite dragons near Ogrila & The Crystal Spine that can be summoned for 35 Apexis Shards each, each one drops a scale that can be looted by everyone in your group. Combine the 4 different scales to get a level 70 BOE blue cloak - Deathwing Brood Cloak. You can then either DE them for a shard, or sell them on the AH for cash.

Cheers,
Stealthy