Hi @epicenterdefacto
The cost of transactions is this;
How much do transactions cost?
These are the costs I see on www.steemd.com:
comments 1,570,000,000
votes 282,000,000
transfers 259,000,000
powerups 259,000,000

If I spend all my resource credits, do I have to buy more?

Answer: No, resource credits regenerate each day by a certain percentage, which is believed to be 22% and it takes 5 days to fully regenerate your entire allotment from zero.

You should have enough in 24 hours.