"Stock sprites" ruin your credibility. They send meaningless or even wrong messages to your visitors. Your graphic must be relevant and authentic. Your own sprites should be used for a reason and push your potential clients towards your main goal – create your brand.
Yes, I know. You're a developer and you use only paint to make sprites.
There are a lot of website where you can buy assets. Or you can visit website like fiverr or freelancer where you can find artists that can help you with your low budget.
Or join to the jams. Like the Global Game Jam or Ludum Dare where you can meet new friends and future colleagues!
