Fishing technically still makes you a profit once you hit 200 since fish and daggers sell for more than the bait, and if you have something that summons a rod then you don't even need to worry about the cost of a new pole either...
So, for something to usually be an issue with the devs
1.) you must make a LARGE enough profit for it to make a dent in the economy (i.e. like multiple PP an hour)
2.) easy enough to do that you can macro it
3.) have a low chance or low cost of failing.
So this is where the fishing in Abyssmal sea was a problem... you made huge profit (I made 10K pp in a 6 hour time period), you could macro it (I read a book while mashing my fishing hot key), and it had a low chance of failing (I had the fisherman's companion and a 200 skill)...
AS such, there are some tradeskill items you can make that are all vendor items that sell for more than the sum of their pieces, however, your chance to fail is so significantly high that its just not worth doing.
Its unlikely this tradeskill purchase is worth the bother.
Shoot - you can take some rusty weapons, sharpen it, and then combine with water to make ore that sells for more than the original weapon, stone, and water cost to buy...