When you say she was mated the other day, how long ago? The vet can give her a jab to stop any pregnancy. This used to be done within 48 hours, but there is now one that can be given up to several weeks later - your vet will advise. Although cost is a consideration in having a litter, the safety of the bitch would be my concern. Keep a close eye for any discharge which could be pyometra, an infection of the womb, which can be fatal if left untreated. Also if a C section is needed (probably minimum of 400 pounds - more if overnight or weekend or Bank Holiday) you could end up losing the bitch and puppies. If you lose the bitch but the puppies are ok you would have to hand rear them which would mean 24 hour care with feeds every two hours. All in all I would be seeing my vet to stop any pregnancy, but if you decide to let it go ahead be ready for a lot of work, expense and maybe heartache.