The most important things are your lights, soil, and seeds ... followed closely by your fertilizers.

A good HPS 600 light system runs around $220 -- if you need to go cheap you can use flourescents or hortilux bulbs -- but why screw around?

Soil is cheap -- I use organic soil with bat guano and other crap mixed in -- works great -- about $8.00 for a bag big enough to fill I'd guess 6 3-gallon containers. Maybe two bags -- $16.00

Seeds - you can use what you got -- probably best for a first grow, then use your money wisely and buy online once you know what you're doing -- anywhere from $20.00 to $250.00 for 10 seeds. Prices vary widely.

Ferts -- you'll probably spend another $20-25 on them and misc other additives. You can get a good 3-prong timer for around $10 or less.

A 25'x4' roll of Mylar goes for about $25.00 if you want to reflectorizr your walls. Maybe some dog chain and s-hooks to hang your lights from -- easy to adjust - $10.

That's a basic starter kit.