Unfortunately we have to compete with people running bots on their validators, which is.. impossible.
But setting the buy price around 12% below market has worked well for me so far, even with cards like chaos summoners. The bot is also a tiny bit faster if you bid on s smaller number of cards (since it doesn't need to check as many).
I'll look into the 'manual bot', thanks for the suggestion :)
!hivebits
RE: I am making market bots for Splinterlands