Do you have any confidence in your personal plumbing is any good? Are you contemplating the potential for dealing with the issues on your abilities? If you are ready, you are at the right place. The advice about making your own plumbing.
Do not pay your plumber until the problem is fixed. You may be required to put some money down before a job is started, but you never want to pay the entire amount until you are certain the job was completed to your satisfaction. You want to make sure the plumber completed everything that they said they would before they get your money.