From: scotchtape51
I agree with making prices go higher. however if something gets to high (for a false example air runes costing 150 each.) Fagex would probably adjust the price themselves.
Since there is a Buy-X option in stores, the price would never go that high, (it's 17 in stores btw). How could it, even if you managed to craft the tens of billions of air runes a month required… People would never buy them…
So you want to try an item that doesn't have a Buy-X option in stores? All prices of every item in RS that are even close to being important, are somehow tied to a fixed value. Mithril ore, is based on the price of 4 coal, plus 1 nature rune required to superheat 1 mithril bar. Which in turn are tied to yadda yadda. I find that most things ultimately end with high-alch prices, but there are so many factors.
OK, so, assuming you managed to gain a monopoly on one item, big deal. No-one would spend 5k for a mithril ore. If they wanted to level smithing, they would go with addy or steel etc instead… Jagex wouldn't change there trade limit ways even if one item was destroyed, there are thousands of items. And, like you said, they are all-powerful, they could just fix the item, either directly or indirectly. Like making a new shop with Buy-X mithril ore, or a mining minigame…
Next, you underestimate the amount of accounts… There are millions of active ones, and less then 60,000 SRL members, (of which less then 3k are active).
Lastly, Jagex could just IP ban you, if you autoed too much and got banned too much, (which is inevitable).
I won't say that autoing doesn't affect item prices, it certainly does, but something like this would result in an Epic Fail all around =p