SpotOn's own pricing page publishes an All-In Plan at $0 per station per month, which carries a published two-year minimum term and processing minimums, with card-present processing at 2.79% + 20¢. It also publishes a POS Essentials plan at $55 per station per month with card-present processing at 2.45% + 15¢ (2.79% and 3.19% + 15¢ for Amex), plus separately priced hardware. A Build Your Own plan is offered at custom pricing for multi-unit and enterprise operators.
SpotOn's own FAQ answers the question "Can I use my own POS hardware or tablets?" directly: "No. SpotOn's proprietary POS hardware for restaurants is designed to be fast, reliable, and secure. We wouldn't trust your business with anything less." SpotOn's FAQ also states that SpotOn provides integrated payments across all of its POS offerings as a single technology partner.