Last week's sharp hike in the wholesale price of beef is a strong indication for higher meat costs to come.
- The "for" in my opinion is definitely incorrect here, since in major cases "indication for" means "a symptom, problem, or situation in need of certain treatment or fixing". In my opinion, this isn't the case. Here it is "a piece of information that shows us something (indicates)". (see indication)
The choice of plural "costs" makes sense because meat prices vary from area to area, from region to region. It isn't one cost, it's a variety of them.
There is a way to rephrase it as follows:
Last week's sharp hike in the wholesale price of beef is a strong indication that higher meat costs are to come.