Warfarin needs blood tests at least every 2 or 3 weeks. I bet those tests are not cheap in the USA. Furthermore you can't have any food with significant amounts of vitamine K or its precursors. There are pills that cost more but don't require any of that. And actually they cost very little or zero, at least in my European country. Prescription only, of course.
What about Warfarin? Its $21 for 30 pills, according to https://www.goodrx.com/warfarin