I probably wouldn't do this unless I'm bored, or wanted to level fishing, but just an idea....

I just started 5 boxing fishing in WG. It's actually not that hard. I usually get 3-5 fish per cast. all the fish you get in WG sell for at least 1g on my server, more like 1.5g min. So that's like 5g a cast easy. I like the idea of selling all the mats for a fish feast right before raid time, like Smooth did. That's a damn good idea.

You can get around a min of 80 northern spices each cooking daily (total with 5 guys). sometimes you can get 120-150 if the daily gives you 2 cooking awards. You sell each feast for 10g - that's an easy 800g.

Fish you need:
6 fish makes a fish feast (all caught in WG), along with 1 northern spice
so that's 480 total fish.
If you catch 3 fish on average every 30 seconds, that' 6 a min or 80 minutes for 480. I think a full cast only takes 18 seconds, so you can do better...
So for around 1.5 hours of work, you can make about 850g. (50g from doing the daily)
On my server the spices alone sell for 4g (there are none on the AH under 5g this second), and fish used to make fish feasts are 1.5g each, which makes the fish feast sell price close to 14g or 1100 for 1.5 hours work.

So if you're leveling up fishing to 450, go to WG and fish, you could probably make 4-5K easy. just don't flood the market with fish. sell some before raid time, that's about it.