Another approach is to require a full lab to create the potions/grenades/etc.
Basically, you have to have a lab to create the items. At 1st level, you basically use whatever small room you can carve out of your home or apartment (and you better have put in the points to have a home; no inn-hopping for you), and the tools and equipment allows you to craft N items per day, if you spend all day on it. There is no limit to the number you can craft and store, though. Well, as long as you have access to your lab. Without your lab, you might be able to improvise some extras based on ingredients and materials you have on hand, but it will be extremely limited.
OK, now you have 100 grenades. Time to go on an adventure? Eh, hold up. If you don't want all those grenades to blow up in your face, you need to pack them away carefully (eg: crate filled with packing straw), and you need a method of hauling them around (no, you don't get to carry a crate of 100 grenades on your shoulder). You can have a handful of them on you at any one time, in prep for any fight, but you need at least a short rest to go back and unlock the crate and restock what you have on you.
Oh, and be careful about anyone casting Fireball on your wagon. Otherwise, fireworks time. (On the other hand, haul that crate over behind the warehouse and set it off, and the warehouse will be leveled. So yes, going full nova is possible, but now you're completely out of your consumable and ineffective for anything else.) And if you get chased out of a city by an invading army, you likely just lost your lab.
At higher levels you get greater proficiency in your craft, so you can craft more per day (and/or better quality), up to the limit imposed by whatever lab space you have. If you want to make better grenades or potions or whatever, you need to spend the money on a larger lab and better equipment. Thus money becomes a significant limiter, with sunk cost in property at every city you want to be able to work on this stuff in. Might be fine if all your adventures are around, say, Waterdeep, but if you travel the world, you've basically just got what you packed in your suitcase at the start, and when that's gone, oh well.
I wouldn't charge the player cost per potion made, or send them on ingredient fetch quests or whatever, but I would charge a cost per month to pay rent and supply costs to keep their lab active. If they try to go cheap, and rent a flophouse in the slums where all the lab smells get the neighbors angry at them, they'd be far more likely to come home to a damaged or robbed lab, which shuts down their ability to build more until they fix everything. A more expensive house means you better be bringing in regular amounts of money, or you might end up defaulting on the mortgage, with the repo office hauling everything away.
In general, money is a limiter, but it doesn't directly affect the power of the player. You don't get more grenades by just throwing more money at it. The number of grenades is limited by time and carrying space. And if they try to get around it with a bag of holding or similar, I would probably either have concoction stability go down rapidly in an alternate dimension space, or just flat out require that the character has to spend time ensuring the stability of the concoctions each day, else risking duds or grenades that go off at the slightest disturbance (or potions that have a chance to roll on the Wild Magic table). This again becomes a time limiter. You can do maintenance on your 100 grenades, but you might not manage to get a full night's sleep afterwards. Exhaustion sucks.
The number of grenades/potions/etc you can carry on you at any given time (ie: before refilling with a short rest) increases over time as you become more efficient at the crafting, and able to create better yields in smaller sizes. Mechanically it's still X uses per short rest, but it also has conditions you have to fulfill in order for the rest to be effective. And of course the reasons it's X times per rest or whatever are very different, and can affect other aspects of play.
There are ways to get around the X/rest limit, but they should also have risks. If your carriage is trying to escape the bandits chasing you, the grenadier might pop open his crate and just start tossing grenades willy-nilly, without regard for the normal numbers limit. But the jostling carriage might knock a couple of the grenades loose, and have them rolling around the floorboards as everyone panicks about the carriage turning into a fireball.
Really, it seems relatively easy to balance a class using consumable items with more stuff that can go wrong in the adventure. The only real problem is: Bag of Holding. If a bag of holding allowed you to bypass all the risks, it would severely unbalance things. I'd either ban bags of holding entirely, or add significant downsides to keeping 'special' consumables inside of them.
Aside from that, most of the time they'd still be limited by the X/rest mechanic, which is easy enough to work with and figure out how to keep it from getting out of hand, and not cause a lot of headache keeping track of things during play. The player could still bypass it, but doing so should introduce significant extra risks as well.
