Dont know if youve tried it but salmon roe,histcarp, and,jazbay grapes are supposed to make the most expensive potion to date in skyrim. I tried it before but my alchemy doesnt have perks and lvl isnt as high in my current 360 playthrough. Whats difficult bout this potion is gathering the ingredients.
I plant Jazbay grapes, I breed Histcarp in my fishery. But Salmon Roe is hard to find because you can only get them from salmon that are jumping upstream. So any other salmon doesnt give the ingrediet.
Your a great ingredient hunter you could prob find an area with tons.
But here http://elderscrolls.wikia.com/wiki/Salmon_Roe