If you have $500, i advice you not use it for build 1 business.
You can try some business such :
- Build blog to be monetized (the method is up to you) but in the first you need to make it popular first. For example is by holding a contest. Lets say the budget is $100
- Get MRR product on many site and compile it, sell with interesting price. Lets say the budget to buy MRR is $200 (i think you can get 11-15 MRR with $100)
Look, you still have $200 on your pocket.