Dear Baconfry, I agree that the balloons are hard to obtain in a single world. I personally am against the idea of having to use multiple worlds in order to achieve certain items. I am okay with the fact one world cannot have both Corruption and Crimson items, but in this case it seems suitable to have it be obtainable in a single world.
However, the biggest problem for me is probably obtaining a Sandstorm in a Bottom. The chances of getting a desert pyramid are near nihil, which I think is just.. illogical. The pyramids are the only way to obtain the Sandstorm in a Bottle. I'm not proposing a change to this, though I do have a solution to this problem.
So, we've got the three balloons to obtain for this item of which one is often unobtainable. What's my solution to this? Well, it's simple: More varieties for the Bundle of Balloons! There's always been the fourth balloon, the Fart in a balloon - I always felt it has been slightly left out, especially when it comes down to the bundle of balloons. After all, the current sprite depicts a green balloon which is not included. Here are the new varieties:
(Basic re-sprites)
It's pretty self-explanatory, I think. The name of each item does not change, just the sprite and the functions of the balloons used to make it. I don't think having multiple variations of balloon bundles would be a problem, after all, they were never stackable.
Now, the fourth item would of course be most interesting because it doesn't require the Sandstorm in a Bottle which is a very rare item, though it would be near equal in power.
This is just my proposal, I think it would be a good addition to your current post. Thank you.