Replacement of the printheads on HP Designjet 9000s is notoriously expensive and can only be carried out by a specialist engineer equipped with specialised tools. this is the generally accepted situation but is not necessarily the case.
With 6 heads, which for an average user will last about a year, taking out a maintenance contract would seem to be the only sensible option.
The cost of each head seems to be around £1600 each with the cost of an engineer on top; therefore to change 1 head would cost about £2000 while changing all 6would cost about £10000 (about 75% of the cost of a new machine which would come with 12 months warranty).
The current cost of a maintenance contract is about £2000 per year but some companies will charge 2 years payments up front.
One option that can be considered is to pay an amount of money into an account during the first year of ownership (during which the printer is covered by its warranty) which will then cover any head replacements necessary during the second year as well as any other parts. it is worth checking the quality of the prints when nearing the end of the warranty period so that any suspect heads can be replaced while still under warranty. it is worth bearing in mind that there is a preventative maintenance overhaul that is carried out towards the end of the first year (for an an average user) which replaces many of the components such as drive belts and head cleaning station and that this is not covered under the warranty. this service costs about £600. it is unlikely that you will have been told about this by the distributor when you bought the machine.
If you are fairly dexterous (and brave) it is quite possible for you to replace the head yourself and with heads being available on the internet from Europe at around £1200 and from China at around £1100 there is quite a saving to be made. on one website there is listed a spacing jig which attaches to the plate to which the heads are screwed; if you can afford the £600 that this piece of drilled metal costs then it will save you some time later but it not absolutely necessary if you have the patience for a little trial and error. i will be covering this process of changing the printheads in the next article.