Statikk Shiv should cost 3400
, have 5% more AS and offer significantly more magic damage for melee champions. Kircheis Shard should have a lesser but similar AoE magic damage effect and also cost more.
Rapid Firecannon should cost 3000 and charge significantly faster on melee champions.
The problem isn't that "crit items are too strong".
It's that "crit items are too strong on marksmen".
A ton of melee champions used to get away with building crit. Now none of them can afford to because marksmen will kill them with crit items first. That is the problem with crit items right now - damage amps and shields have become so prevalent that in a midgame teamfight marksmen can right-click entire enemy teams away with just two finished crit items. They shouldn't be nearly this cheap to buy, and should retain at least some relevancy for melees.