Cup and cone are far from dubious. Do not fear them at all. As far as "sealed", the Deore hubs mentioned above have rubber seals. Most hubs use some sort of seal - labyrinth or the like. Based on what you purpose is, these may suit you fine. As far as them being not as good, that comes with context. It sounds like they will suit the purpose of this build. I approach everything I do with a goal of maximum longevity for reasonably spend so my previous answer was colored by that. In the future, you will get better answers if you give more information up front. When you make "cheap" so primary a factor that it is in the title of the thread, it might send the wrong impression.