Hiya Noodle
Mine cost €175 in Sligo. This involved a site visit, a chat about what we wanted, an A3 plan (pretty detailed) for submission to the planners and about an 8-10 page document for them as well specifying plant types, numbers, sizes etc. The main part of this is a layout of the mixed native hedging we intend planting on the boundary.
No problem with the planners and all in all we are very happy!
I just put together one of the site drawings detailing the planting scheme and a list of the planting that would be done, but seeing how irritable most planners seem to be these days, I'm not sure it's worth the risk!
We had planning approved earlier this year - the Architect put a landscape plan on the site map at no extra cost. We had no issues with planners. He had a key on the plan to refer to that inducated tree/plant types eg decidous etc and their approximate sizes. Nothing too fancy at all.