Replication means more trials, thus more costs but it only allows you to study whatever interactions the original trials already allowed you to study. It also allows for the estimation of experimentation error.
Randomization is essentially conducting trials in no pre-determined order. There’s no reason to believe conducting trials randomly will cost less (in fact, it may very well cost more) but it helps overcome (or avoid) bias. It also means that noise factors are equally as likely to be present in all trials.
Also see Design of Experiments