A couple of things we have done for less than $100 over the past year:
1. Switched to Air Voice-we had to buy inexpensive SIM cards to do the switch & maybe a few other things. I think the overall switch cost us @$25 to get our phones to adapt, but we are saving $175/month over what we were paying previously.
2. A dryer vent cleaner. I think this was closer to $70. It got to the point where my dryer was taking over an hour to dry a load. After cleaning out the hose & vent, it takes between 30-40mins. I now I could be hanging more clothes up to dry, but this is one of my luxuries.
3. We bought a Roku (about $80-one time purchase) to be able to have Netflix at home. This allowed us to get rid of cable. We have the local stations and we use Netflix. Another one of my luxuries, but a fraction of what we were paying before.
4. $50 can give you a great start on a veggie or herb garden. We have to grow everything in pots where we live. So, the seeds are cheap, but the pots were more expensive.
5. I spent $15 on a large pot to begin canning. Also bought canning supplies & jars. To get started, it definitely cost under $50. This is a great way to use up surplus from the garden or leftover fruits & veggies. I usually prep & freeze the fruit/veggies until I have enough to make a batch or two. I recently made a pear/raspberry freezer jelly & a pineapple/orange/jalapeņo marmalade. Both were pretty freaking good. Found the recipes online, but you can also make pickles, salsas, etc.
6. Bike trailer - $100 Nashbar - to cart around my toddler & groceries. Was driving to the store & everywhere else before this purchase. Looked on Craigslist for a while, but ended up buying new.
7. Started making some household cleaners. Most of the ingredients are less expensive and overall you should/will come out cheaper than store bought products. The most expensive cost was essential oils. You normally only use about 10 drops, but I had sticker shock. Fortunately, a little goes a long way.
Just a few things to give you some more ideas.