I'd say, to me, speed loaders are well worth it. Loading a single magazine over and over again at the range or on a hunt is a real pain in the, well, you know.
I have a 3D printer and found a speed loader file someone else created. It's not the same as the model Stoti showed and not as nice. It's not nearly as nice as the model sold by UA, as I load all pellets skirt first manually into the speed loader. Yes, that's a pain in the, well you know, but I printed 10 so I can preload 280 shots. Two fit into a JSB Pellet tin quite nicely. For me, that works great. I load them all at home where it is warm and my fingers still work.
If the speed loaders are the type that you drop a bunch of pellets on top, shake it and the pellets just fall into place, it's worth every penny of the $20 or $25. If you have to manually load each pellet skirt first (Like I do with the file I selected) you need a bunch of them.
So, yes, I think they are well worth it.