Weapon attachment costs for items that we cant change?!

It looks annoying but it's just a balance thing when you want all guns to get 100 points (or 60 for handguns). Basically you could make the magazine of the SV98 free, but then that gun only has 95 points to distribute.

It's the same when it comes to the minimum cost of a lot of attachments: you can make them all free instead, but then different guns would have different available points.