considering that some people think 5 is a lot and others think 100 is a few, I am not sure where you fit in here.
I have done both the screen printing, the plastic stencils - both commercial ones and ones I made, and have also done the iron on design things. I have also gotten the fabric paints and used the little paint bottles to put the designs on T shirts.
They are all fun and easy. I much prefer the drawing the design on with pencil, then painting with the little bottles. Can spread the paint with artist brushes while doing this too!!
For screen printing all you need is a form of some sort, even scrap lumber works well. a tray, some squeegie sponge things and the willingness to make a huge mess.
None of it is any more expensive or less expensive than another when you get right down to it. You spend as much as you want on any of these ideas.
You have to buy paint of some sort, brushes, the other items to each idea and of course the Tshirts.
Go to YouTube and put in Silk Screening, Plastic Stenciling, etc and you will find a wealth of videos on how to do these things.
Try the National Serigraph Society of the U.S. An artist named Anthony Velonis was one of the pioneers of the method of producing art work by serigraph. Guy MacCoy held the first one-man show of serigraph art works [screen printed] in 1938. Serigraphs are original art works not copies. An original screen print is one in which the artist has created from his own design using colour stencils which he has executed.