How much should front brake pads cost?

[Dead Eye]

The pictures seem to indicate that there is loads of life left in those pads imo

I'd suggest your problem is elsewhere.

ChristoT recently had an issue with his front brakes squeaking a lot so when he was round mine the other day, we removed the callipers, removed the pads, put some copper grease on the back and reassembled and now the squeak is completely gone. You can get a massive pot of copper grease for less than one of those cheap sets of pads you found