If you want the exact fabrics as in the photo, it is usually cheaper to just buy the kit. If you are willing to substitute some or all of the fabrics, then it is cheaper for you to do so.
In many cases, you can't get all the fabrics at only one store. That means more expenditure in time, gas and/or shipping charges. What you are linking to is a BOM rather than a 'kit' and nearly always, you can save a lot in shipping if you just get the pattern and choose similar fabrics from one or two locations. BOMs include monthly shipping costs and often have a more significant markup.
Now, you may have trouble finding the pattern - that is often due to licensing during the course of these BOMs. If you are willing to wait a year or two, the pattern will become available. The question is 'will you still love it' in two years? If so, buy the fabric now and wait for the pattern. If not, be ready to buy a different color combo because color palettes seem to change every couple of years.