Front touch glass replacement

That's not really a question we can answer here. iFixit is a resource for you to be able to do your own repairs and as such there is no labor cost since you're doing the work yourself. Thus the only cost is for parts and perhaps tools, which you are responsible for finding yourself - unless iFixit sells the part you need, which in this case they don't.

I might also add that although you can purchase the front glass quite inexpensively, the effort, expertise and specialized equipment required to separate the display from the touch screen and reglue a new glass on makes it quite cost ineffective. A quick search shows complete display assemblies for you phone for as cheap as $20 USD, so at that price point it doesn't make any sense to pay for a front glass replacement since it would likely cost more than a new screen.