Just looked it up... we had every season a transfer for the B team in the ~5m range (some 2.5m). Mostly shit players though (in retrospect?!).
Maybe the club is paying a bit more to go after the better ones. Saw that most of the highlights of this Varela guy are on Portugal NT youth level.
I think it is likely that the better talents are gonna cost quite a bit more than 500k-2m. I have read this Varela guy can cost us almost 10m (addons included) if he makes it. I consider this the biggest investment for a young player in many years. Mostly like Bergvall that the club missed.
Previous names have been much cheaper. I think clubs like Dortmund and the portuguese big 3 that end up developing young players and selling them for big fees buy outside talent for more serious money in general. Just a suspicion I have.
Just an example. 17 year old Isak cost Dortmund 8m from AIK in 2017. Not 500k or 2.5. You have to also take into account that usually the selling clubs place value on their better youngsters. To attract a bigger talent, you usually pay a bit more than usual.
Club probably gone after lesser talents hoping to develop them through La Masia, but it's a bit late to develop a 16-18 year old player, the fundamentals of the player are mostly formed. You need better quality at that age already, and for Barca to just provide the finishing touch over an existing solid set of skills. Those solid fundamentals simply demand a higher price, closer to 10m usually, possibly even more.