Portable pitching mounds are becoming increasingly popular from Little League to College & even Pro Players for off-season training, due to the low maintenance & portability. Developing & maintaining a dirt mound year after year can become very costly, not to mention inaccurate, resulting in improper training & a potential safety hazard.
A portable mound can easily "pay for itself" after only a few seasons of use, and can even be used as a "multi-tasker mound" for multiple fields if needed.
The keys to consider when shopping for a portable pitching mound are:
Include tapered edges, to allow the mound to lie flush with the ground. Creates safe environment during game conditions, such as pick-off moves, players running across mound to catch pop-flys, etc. More expensive than "practice mounds".