That's in season so it will be more competitive / expensive than in the summer. I stayed in WPB at two different marinas
last fall and both were about $1100/mo for a 27'
Look at Lake Park just north of WPB. A nice little community there and the prices are a bit more down to earth. You will have to make a reservation well ahead of time.
Look at the activecaptain interactive map. Lots of marina info to be gleaned there. You may be able to find something reasonable, esp if you sign a long term contract