Whats the best accurate seo rank tracking tool

I need to monitor 2,000 to 5,000 keywords for a client who is paying me fairly well, though not exceptionally. Unfortunately, I’ve exhausted my credits in both SEMrush and AHREFS for this task, and I’m hesitant to ask the client to cover additional expenses. What’s the most cost-effective approach to address this? Currently, I’m considering SE Ranking as it offers the cheapest daily keyword checker, but I’m also open to less frequent checks if that would be more economical. Has anyone else encountered this situation and found a cost-effective solution for keyword tracking? Ideally, I’d like to integrate this into our process for all clients, but for now, this particular client requires a more detailed keyword monitoring approach.