I made around 150 dollars using my initial investment of 50 dollars.
What did I do? -
My Lawn Mowing Service
Biggie may not accept this as I used my old lawn mower. But who cares

.
I repaired my old lawn mower which cost me 35 buks (Did it all by myself, I'm a crazy engineer

). 15 buks is my service charge

.
My new lawn mowing machine was then lended to a local school for 5 buks / day. I can't believe those morons agreed to pay me 5 buks per day

. they have been using my lawn mower since past one month and I'm making money.
Not a bad start
Anyone else?