I'd have thought that was enough. It depends on the size of the kitchen, and the quality I suppose,.. and of course how much of the budget you intend to spend on appliances, sink and taps, and on worktops.
You could spend 3,000 on appliances, sink and taps, and another 300 say for worktops. That'd leave you several thousand for cabinets and fitting.
You want chipboard, mass produced cabinets, yes? So I'd say call Woodworkers.ie, or any of the other kitchen crowds, and get some quotes. You have got some quotes already.. if these are all too high then perhaps your kitchen is very large, and they are only charging a fair price. You can see Woodworkers.ie cabinet and door prices online, so you can make up your own quote, and compare it to those you've been receiving.
Kitchens would be competatively priced at the moment. Can you describe the type of kitchen you're looking for?