When I was burning emulsions for screen printing, I just got a "sunlamp" bulb in a short stand. The selection for UV lamps/bulbs/sources is even wider nowadays I would guess...here's what one guy said as possibilities:
. . . sunlight, un-filtered black lights, quartz, mercury vapor and metal halide lamps (of course some sources work better than others, and like computers faster usually means more money)
More ideas and discussion in these search results:
Or ask in this discussion forum at Craftster (one of their sub-boards for screen printing):
All three applications have their place and are all used by big clothing companies. Do you have any shirts with a tag-less label? That's most likely a heat transfers.
The size of the company has little to do with which method they employ. The project dictates the decoration method. Traditional direct screen printing is used for printing a few dozen all the way to millions of units. Cutting vinyl is great for creating a one of kind image for one-off customization or personalization. You can have heat transfers screen printed to help manage inventory, decorate heat sensitive items, or press shirts live at an event.
As far as quality is concerned all can be employed properly and wash and last the life of the garment. A novice screen printer and under or over cure the plastisol ink impacting washability. The application of a vinyl or a screen printed heat transfers can also be done improperly (using incorrect time, temperature or pressure) affecting the print quality.
You want to look for the most efficient decoration method for your application.