A lot of reputable shops carry Stage 1's for decent prices.
Full Force Diesel, Unlimited Diesel Performance carry them (can probably get a reman set for $900 or so), and Swamps Diesel has a great selection too.
Intercoolers get expensive if bought new (the Banks is $1,400 but an awesome cooler), but a used Super Duty intercooler can be made to work if he can locate a few Super Duty 7.3L items.
Some good tuners: Swamps Diesel, Beans Diesel, Gearhead Automotive, Total Diesel Performance, DP-Tuner, and plenty more. Six-position chip will call for $400 to $500.