Square availability
Signing up for Square involves supplying your bank routing and account numbers, so Square can deposit your money. Only the first $1,000 of each week's charges lands in your bank account immediately. Anything over that is reviewed by the company's auditors; it can take as long as 30 days before you see the rest of the money. That could be a downside if you sell a lot of used cars.
Then again, that's just for first-timers. The more you use the service without incident, the higher the company will raise that $1,000 threshold. In fact, if you're willing to share more details about your business with Square upfront, they'll raise that threshold from the start.