If you don't mind doing a little work, the 1/2 inch compression fittings for drip irrigation from DripWorks offer an affordable solution for many applications. These are the lowest-cost fittings for 1/2" tubing. A compression fitting requires neither glue nor clamps, but it does demand a bit more effort to install than other fittings. These fittings hold very well up to 70 PSI.
If you're searching for polyethylene tubing compression fittings, you'll find a wide assortment of products to help you adapt your watering system to your environment. Whether you're looking for a 1/2" irrigation coupler, a compression elbow or compression cross, you'll find what you're looking for here. We also have compression Raindrip fittings on this page, including a Raindrip universal adapter coupler.