To be honest, the installtion would have to be viewed to acurately price any job of this nature, ie, where condensate will go, some sites have flueing issues (ie. maybe flue extenstions required to hide plumes or move them away from a neighbouring propery) then discuss with the customer their specific needs, and price a boiler suited to them (ie, system or combi or thermal stores)
Usually price begins around €1800 and can go up somewhat from there....
Remember, always use a registered installer, maybe get a recommendation, and always get a receipt in case you have trouble afterwards,
Sometimes in this case cheaper is not always best, as some 'cheap' installations (or should i say installers) do things like not bothering to flush the old system, or add inhibitors when filling the new system, in these kind of cases within 1-5 years the trouble starts, usually with things like noisy (bubbling) heat exchangers leading to power flushes (expensive!) and other treatments to combat the poor inital installation....so be careful you know what your getting if price is too cheap, usually something is amiss.......better to pay a little extra and have a good boiler for 10-20 years than find yourself replacing it again in 5 years time!