I was in a similar situation to yourself. Got three quotes as follows (prices from memory):
1. Rotavate, level out and seed area, plant 60 shrubs in a border area - about €4,000.
2. As above, plus a little bit of tree pruning and putting mulch under trees (so that there is no grass to cut under the trees), put in a few decorative boulders - about €6,500.
3. Proper landscaping guy (affiliated to whatever the association of lanscapers in Ireland is) - put 4 inches of topsoil across the whole area, level everything out, decent amount of tree pruning and hedge clearing - about €12,500.
Didn't get anything done in the end as we ran out of time and money this year!
I'd be interested to see what other replies you receive and what you do. One thing I would say if to get several quotes as each person that gives you a quote also gives you a different angle on things.