My experience is much like Duffyjr's; I find the ease of use and effectiveness of the Urnex products, Descal and Cleancaf, worth the expense. Vinegar was the most recommended cleaning agent for decades and still works, but I find today's specialty products work better and do not have the strong odor of vinegar.
It has been a while since I purchased Urnex products but, when I last did, I found by buying their equivalent commercial products in quantity, from an on-line restaurant supply vendor, the unit cost could be greatly reduced.