Mmm...ROI = Return on Investment.
The power items are a risky business. I don't go for them unless I have the money to blow and it's sort of like a trip to the casino, fun in small doses, but risky in large ones. I have an agenda where I'll synth 1 power item, and a bunch of smaller items that turn a decent profit. Maybe you aren't researching your craft enough but there are other ways to make decent money without risking your savings. But if you don't have that money to blow initially, I'd suggest slowly working it up before you shoot for the high hoops. Usually, 2 smaller profit items with less risk add up to that power item with huge risk.
Clothcraft probably has it's profit items, but it doesn't necessarily have to be the Vermillion cloak or items that require a huge investment. My friend made a decent fortune off a skill up item, it's a rare as heck HQ rate but it was easily a clean 1.5mil profit. And from what I know it doesn't cost more than a low 5 digit price to make.
A lot of items also have a margin in which you'll lose money on the NQ, but make massive fortune on the HQ. Usually you make these expecting to get the HQ which will negate the losses that it took to get it. Not necessarily meaning you're guaranteed to get this as such, but with the right knowledge you will.
BTW, was that guy Jebustherussian? :[ Sucks he quit over that...I didn't know thats why he left. Well like I said in another post, the fail rate on all synths past the trivial level are constant, as in, that level 5 synth will still fail at the same rate for a lvl 5 as it will for a lvl 100, as it will for a lvl 500 in that craft (were 500 possible). It seems to hover around 3-5% based on day/moon. There's no stopping this.