It seems that publishing post in Memo.sv is much cheaper than Memo.cash, my first post spent 248 sats, which is about 4*10^(-5) dollars, but for memo.cash, it is about 0.001 dollars. That is 25 times difference.
I charged 0.001BSV which is only 1.6 cents, but I can publish hundreds of posts like this. That is really cheap and here is basically no limit of words.