Actually, in the cosmic scheme of things, tabloids are more expensive to produce. More of the paper is used for margins because you cannot publish material across what would be the centerfold of a broadsheet page. If you are looking to provide students with experience that can be translated to the profession, broadsheet is the only way to go.
Tabloids are few and far between.
Tabloids do have one significant advantage in some regards that is a disadvantage in others. A broadsheet requires better photos and graphic elements and more effective layout strategies. Tabloids offer far less of a challenge for a page designer and often devolve into stale, pre-formatted approaches. Of course, if you don't have a very strong visual side to your operation, going to a tabloid format would help you hide this.