Thanks you all, this is helpful

I can see big structures sub-contracting smaller guys for small orders, is this a reality or a wrong idea?
Possibly, a good relationship with a screen printer to use as a sub-contractor is always a good thing and could be reciprocal.
Besides the money aspect. What are the technical factors that would require screen printing over heat press?
Number of prints/pcs required and the number of colors, there are many different types of transfers so it's hard to say where to break off would be so to me it's in the number of shirts required to fill the order.
How about the quality of the job? and regarding the sale, what do people are more compelled to buy, transfer/vinyl or screen printed?
It's hard to beat the quality of a screen printed shirt (done correctly), that said some garments just lend themselves to different decorating processes, dye-sublimation on light colored poly, or vinyl names and numbers on a football jersey, or DTG for full color photo-realistic prints on 100% cotton.
In my mind screen printing is the high production (large numbers of shirts) side of the garment decorating business for the lowest cost per unit....nothing else really comes close if you had to print 1000 shirts in the cost to produce.
In your opinion, how many shirts you need to screen print before holding a fair knowledge of the techniques. How would you describe the learning curve?
Since we don't screen print that's a tough question for me to answer but I'll give it a shot, to do basic one or two color screen printing I'd say the learning curve with quality equipment is marginal, but to do half-tones, spot colors, discharge, water base, I do believe would have a steep learning curve.
The other thing is the basic equipment to do high quality screen printing is costly, you would need a quality press with micro registration, a flash dryer, an exposure unit, a dip tank, a washout booth, a printer, a RIP, screens, inks, squeegees, emulsion, an conveyor dryer, etc......and of course years of learning.
