Are you asking if it daft to pay full price for originals when compatbiles are so much cheaper and just as good? If it gives you peace of mind, and you don't do loads of printing, then it is not daft. If you print a lot of pages, then perhaps it is daft. These days, printers are not hugely expensive. Even if they do go wrong just after the warranty expires, you don't have to cry all the way between the bank and PC World to buy a new one.
The subject has been done to death on this forum. Have a search for "inkjet cartridges" or "compatible" and see what you come up with.