We are often asked why most mini split systems do not come with line sets. Most of the major manufacturers do not believe in packaging line sets with their systems for several reasons. Requirements vary for every installation. If a manufacturer packaged a 25 foot line set and you needed 50 feet to complete your installation, you would either have to buy a 50 foot line set and not use the line set which came in the system (which you paid for in the price of the system) or use a coupling to add on to the short line set. Since using a coupling is not recommended, manufacturers want to avoid this from happening. When you use couplers to increase the size of a line set, you are adding four potential points for leaks.
Another reason most manufacturers do not include the line set is they simply do not make line sets. They would have to buy them from one of the many line set manufacturers. This would add to the cost of the system the price of the line set, but it would also add other costs that are hidden. Freight charges from the manufacturer to the distributors would be higher which would add to the cost of the system.
When you shop around, you may run into some brands, usually promotional brands that include the line set. These companies will do this this as a promotion in an effort to make their product look more enticing. Since many of these companies lack support and parts availability in the United States, they try to do something to bring attention to their product. The line set in the package may seem like a good value but is it a better value than a name brand manufacturer with full product support and parts supply to take care of your needs for years to come?
This issue really comes down to simple economics. You buy only what you need for your installation and in the long run, that will be more economical than any prepackaged deal.