I think you may not have considered to cost to build such a farm yet. Sugarcane may be an easily cultivated crop, but to produce mass amounts of it requires so many observers (an alternative way is to use redstone clocks, which require either hoppers, repeaters or comparators) to drive the system required to automatically harvest the actual planted sugarcanes.

With the math, assuming you want to make 30000000 every 24 hours...

You need 30000000/500 (60000) stacks of sugarcane per day.

That's... 60000/54 (around 1111 double chests) of sugarcane.

Hoppers only can hold 5 stacks of items. With that in mind,

In vanilla Minecraft (assuming the mechanics work this way) hoppers transfer around 2.5 items per second, but only if connected horizontally. They transfer items approximately twice as fast, so 5 items per second.

Since 64/5 = 12.8, it should take 12.8 seconds to transfer a stack.

You need 60000 stacks.

Assuming your water transport system is at 100% efficiency (highly doubt so but it's theoretical)...

In a day, there are 24*60*60 = 86400 seconds.

86400/12.8 = 6750, which means that in a day (with one hopper that collects all the sugarcane), you can only collect 6750 stacks. Not enough.

Let's say we have more hoppers.

Since one hopper will only produce 6750 stacks in a day, and we need at least 60000 (60k) stacks...

60000/6750 = approximately 8.89 hoppers. Let's say 9 hoppers, working at peak efficiency.

One hopper costs 25k.

That's 225k, just for the hopper cost. At 100% transport efficiency.

So the collection part costs 225k. Not including the water any everything.

Sugarcane, in optimal conditions, grow once per 1088 seconds. Assuming that no grow time is wasted (all sugarcane is harvested once it grows beyond one block, which is basically impossible, but let's just assume it is somehow done), you need 60000 stacks (60000*54 = 3240000 items) per day (24 hours) to make 30 million.

One day contains 86400 seconds as I said earlier.

86400/1088 = approximately 79.4. Let's say it's 80.

So one block of sugarcane will only produce 80 canes a day.

But you need 3240000 canes, not 80.

3240000/80 = 40500. You need at least 40500 blocks of sugarcane to reach the minimum amount of blocks needed (it actually is a bit smaller than the minimum), to actually create the needed amount of sugarcane.

For actually enough sugarcane to be produced, let's just add around 500 blocks to it to increase production per day by 500*80 = 40000 items (312k extra produced for insurance).

So in the end, you need at least 41000 dirt blocks, pistons, and redstone dust. Note that the 40k item production increase per day is enough to negate the possible reduction in production per day required by the assumed 100% efficiency and peak condition growth of the crops which are both impossible conditions.

64 pistons cost you 4800. We need 41000 (41000/64 = approximately 641 stacks). 641*4800 = 3076800, or, around 3 million and 77k.

It costs 1600 to buy one stack of sugarcane. We need 41000 sugarcanes to actually start our farm. So, around 641 stacks of sugarcanes. 641*1600 = 1025600.

It costs 800 to buy one stack of redstone. Same logic : we need 641 stacks. But this time it costs 800 instead, so half : around 512800 dollars for the redstone.

You still need dirt. Dirt costs 250 per stack. You need 641 stacks. 641*250 = 160250.

512800+1025600+3076800+225000 = 4840200.

For some, 4.8 million is cheap.

For some others, it is not.

Remember when I said you need 41000 dirt, redstone dust, sugarcane and pistons to have enough harvesting for your farm? Looking at the automatic crop harvest design, you also need a water transport system. So for one unit of automatic crop harvesting, you need a space of at least 4x3x3, or 3x3x4 (x, y, z). That's at least 36 blocks.

41000 units of sugarcane, automatically being harvested.

36*41000 = 1476000.

That's how many blocks you need. Assuming you're gonna make a cube structure for your farm,

I'll cube root 1476000.

It's around 114 blocks on each side. Because you need walls to hold the water in and also the space for the hoppers and chests, it's around 118 blocks per side to be the most compact.

And don't forget the lag it'll make

(You also need multiple people to use sell wands on the chest as people have to sleep too).

118 blocks per side. Assuming you use cobblestone for the walls (not scaffolds), that's around 118^3 - 116^3 = 82136 blocks as an approximate. That's 82136/64 = approx. 1283.3 stacks, so to be secure let's just say 1284 stacks of cobblestone is needed.

One stack costs 200 (cobblestone).

200*1284 = 256800.

Add that to the aforementioned cost of 4840200 (+256800) = 5097000, which is basically 5 million.

And don't forget the work that needs to be done laying all that for this cost.

To be honest, I doubt you can finish it in 12 hours without help from a team.