Yes, it is very likely that a procedure performed by a plastic surgery resident would cost less; what I would be concerned about is the quality of the outcome of the procedure performed.
There is no doubt that a board-certified plastic surgeon will have a greater experience level than the plastic surgeon in training. I would suggest starting with the American Society of Plastic Surgery and/or the Aesthetic Society of Plastic Surgery to obtain a list of well experienced board-certified plastic surgeons.
Then, I would suggest you visit a few surgeons whose practices concentrate on aesthetic surgery. Ask to SEE lots of examples of their work AND preferably speak/see patients who have had similar procedures done.
Be very careful with your decision-making. You will find, while doing your due diligence, that there are many different “specialties” who will offer their services to you; again, I strongly recommend you concentrate on surgeons certified by the relevant Board of Plastic Surgery.
I would also suggest that you do not base your selection of plastic surgeon primarily on costs of surgery; keep in mind that revisionary surgery may be more costly in many ways. In other words, I would suggest that you save up and have the procedure performed by a board certified plastic surgeon who you feel confident can deliver an outcome that you will be pleased with long-term. I hope this, and the attached link, helps. Best wishes.