Here are some rough (low) estimate prices, which if you've done this before you'd probably be able to get by on. Not knowing what you need and the time it takes to figure it out may not be cost effective if you're just trying to make a couple shirts.. Then again, expensive is relative...
exposure unit (diy vacuum lid c/ metal halide light source) - $200 if you're thrifty + time
4 screens - $100
cheap press - $500
ink - $30 - depends on how many you want
emulsion - $40 - depends on how many you want
other associated chemicals - $100 - depends on how many you want
shirts - depends on how many you want
Time to get it right - PRICELESS, unless you have a lot of it
Good luck