I hope you guys aren't serious about that. Wealth by level is assumed equal for all characters.
The point is, while your rogue is buying hundreds of potions and using them, other characters have something to show for their money at the end of the day, besides broken glass.
That is a ridiculous exaggeration, until the very highest levels when such expenditures are trivial.
At low levels, say 1-5, the rogue doesn't even have the tools for ranged sneak attack. He is just a rogue with quick draw and TWF, maybe precise shot. He needs to flank or surprise attack, just like every other rogue. If he has flasks at this level, he has at most a dozen, for high AC bosses. This is less expenditure than a cure moderate wounds potion for the fighter.
After level 6-8 (rapid shot or his first iterative attack at +6 BAB) he has a reason to carry flasks. He will probably want to use 1 per round, for his iterative attack which will otherwise probably just miss. Assume 5 fights/level, 8 rounds/fight, with full attack every single round, thats 40 flasks, 400 gp/level. The wizard spent more than that on scrolls. Again, this will spike for fights with high AC opponents, but it will ensure damage in those fights.
At high levels, when the rogue is churning out 4-8 shots per round (2-4 from BAB, +2 from Improved TWF, +1 from Rapid Shot, +1 from haste) he can probably reach a couple of hundred shots per day (say 40 flasks per fight, 5 fights per day). Thats 2000 gp for 5 high ecl fights. Hell, he spent more than that on charges from his Greater Invisibility wand. What did he get from that? More than 200 average damage per round. He can solo kill with damage most CR 17-20 monsters in 1-2 rounds. If target is only fire or acid resistant, not immune, he drops to a feeble 160 per round.