Newbie here, quick question- what is the benefit of screen printing onto a transfer? Why not just screen print to the shirt?...funny. Believe me, you are far from ignorance. You are just asking questions, that's all.
No, I don't use digital transfers much (computer/ink jet etc.). Also, Im not a designer.
Around here, we make the transfers with screen printing equipment. The artwork is provided by the customer, we make the films/screens and screen print the designs on transfer release paper.
These types of transfers usually designers/brands don't make them themselfs, they contract out the making of the transfers to transfer makers.
But, if you are starting out, I think you can get a bubble jet printer for $ 50 or something, it does have it's benefits like it will enable you to make full color transfers at a very low cost, one off's. But the quality is not the best to enter the Branding Market nor to be sold at commercial level.
It really depends on your budget and your goal.