pianist?

That really is very individual. I got quotes from $400 to over $1000. Gigmasters.com is a good place to start.

I play piano at Saint Athanasius and Saint Lucy in Long Beach. Our prices there are 150 and $220 when a singer is added. I suggest to consider if your pianist is driving from far away...

We're paying $250 for 2 hours.

As a violinist (pianists may charge differently), I usually play a wedding for around $125-$175 for the ceremony depending on if I am playing with other people (discount for a quartet, usually--just because I feel otherwise it is very tough for people to pay) or carrying the load alone.

The longer I am playing, the less I charge per hour. For example, if I play the ceremony and reception (one hour at the reception cocktail hour, usually), I may charge only $200 for all of it.

If I have to travel a long distance, I like to take that into consideration with the price that I quote. If it is too far, I sometimes don't take the job.

Not sure what the going rate would be in America, we are having a London wedding singer pianist. You could request a quote on her website to get an idea of cost http://www.wedding-singer-pianist.co.uk/wedding-singer-quote.html

I think were paying 150 for just the cocktail hour