Giving offerings on a budget is pretty hard.When you're so strapped for cash that giving something from the dollar store is too expensive, it is really, really hard. Some people would tell you that the offerings don't matter, do what you need to to survive. Other people would tell you that offerings are necessary and you should 'eat more ramen' so that you can make what they deem acceptable offerings. When you're at the point where you want to give offerings but literally have no funds to go buy stuff, it is really tough to know what to do.
This is where I think you need to scale down what you would give as an offering. A simple glass of water is a perfectly fine offering to give. A pinch of salt or spices would be another offering that you can give. Because salt is something of fairly high value. You may not think that given the abundance of it that we have in our lives here in the USA, but it is something that actually is pretty expensive in many parts of the world. Indeed, the word salary has its origins in things dealing with salt because that was how the Roman empire paid their soldiers (among other ways). In the medieval period of Europe's history, seating at the table would demonstrate your rank. If you were of high rank, you were seated where you had access to the salt. This is something that persisted in to the Victorian era.
Spices have a similar history and value. There is a ton of history demonstrating the value of these things. Even if you have a salt and pepper packet that you got somewhere that they were distributed for free, you can still give that offering and have it count for a good deal.