No, on the contrary. The larger the engines get, the more expensive they get. Just look at the massive amount of full-scale tests they needed to get the F-1 engines of the Saturn V main stage running smoothly. Now imagine, you spend all this money to design a huge engine, and you want to manufacture it. You will need a top-notch machine park to do that. Making such an engine includes a lot of steps, like getting a huge chunk of space alloy, and milling almost all of it away, closing the cooling channel using a slow galvanic process, maybe some electron ray welding here and there.
Simply put, to make a huge engine, you need huge amounts of raw materials, huge machines and a huge permanent staff to operate all of them.
Now, on the other hand, if you want to make several small engines, the design becomes less risky and you don't need such huge machines. What's more, since you now need many more engines, you have something resembling a production line, and all machines are operating at the same time, rather than each engine going through a process like in a manufactory.
At almost every step of the way you save money, but several smaller engines are generally heavier. An even greater downside is that, if you need every engine to work for your rocket to reach orbit, you end up with a larger chance of failure.
SpaceX has some redundancy planned in, but that comes at a further cost in terms of payload.
In the end it comes down to cost per kilogram to a target orbit to the customer, and the amount of factors that have an influence here is way too large for an SE answer. SpaceX bet on clustering, Europe will continue to go with large engines. Only time will tell who made the better call.