Why do you have to make it playing as an iron man even easier than it is? I mean, you guys want void, brawler gloves, then helm of neitiznot, just play regularly if you find it too hard?
I really like playing as an iron man, only because it is a challenge. Some people think it's fun to play as an iron man because it's about getting your own supplies and killing monsters for armour. That's not the entire deal, it's supposed to be harder than that.
Now, I do agree that it's fairly hard for iron man players to make prayer potions, and I love it. It is not mandatory to catch manta rays for snape grass, there is monsters to kill, and they are very easy to kill without the use of prayer:
Werewolf: Snape grass is a uncommon drop from this monster. This monster is found in Canifis near the bank. < Kill and bank for more food.
Dagannoth: 2x noted Snape grass is a common drop from this monster. This monster is easier to kill than a werewolf, you won't need to bank as much as you will be banking at Canifis killing werewolves.
Gorak: This is a strong monster which requires 78 slayer and drops only 1x snape grass, so this clearly is not a option for new iron man accounts.
^I've listed these monsters because what most iron man accounts start off doing is training combat / slayer, so it should be very easy to kill these for snape grass / prayer potions.
What I do and what is suggested to do is start off by training fishing to 90 (mantas) / 99.
Why? Because at some point playing as an iron man you will run out of food and you'll have to train fishing for more food. You won't be able to use Grand Exchange like the regular players.
Now for the regular players
Most regular player's goal is achieve max total level. Fishing will be a part of the goal, meaning people do train this skill. And when they do, most of them sell the snape grass for money and that's how snape grass get ingame.
Catching mantas and picking snape grass is a great deal for earning money for low level / new players. If we add more methods of getting snape grass, it clearly won't be a good way for earning money as more items get ingame > the lower the price gets.