I don't have a budget in mind, I don't want broken cranks / misery along the road that's all.
I also don't insist on square taper - it was the choice of the producer/dealer of the bike.
The bike is a travel bike, a Dutch brand "Santos", model "TravelMaster3+" customized to fixed gear by them.
The bottom bracket has an eccentric to tension the chain. Does that limit choices (square taper, ...) in any way?