Do some reading on the site to learn what the basic requirements are for him.
For filters and submersible water heaters
www.bigalsonline is, IMHO, probably the best place to go. (You want a filter rated for 3X the size of his tank, and for the water heater allow 5 watts/gallon of water to determine the wattage you'll need.)
For clamp lights (probably the easiest way to go, you'll need 2), go to places like Home Depot, Lowes, hardware stores, etc. You can get a Reptisun 10.0 compact flourescent to screw into the clamp light for $22.99 at big al's as well (this is cheap compared to what you would pay in Petco or a similar store). Put a regular lightbulb in the second clamp lamp and position both over the basking area. For the lightbulb, use whatever will get the basking area temp 88-90F. For thermometers to check the basking area and water, you can check big als or even get them at a place like Walmart.
For the basking area, as was mentioned previously, you can use a flower pot turned upside down. You can buy one (a turtle dock seems to be popular with keepers) in a place like Petsmart or Petco, or search on line. You can make one as well--look at some of the pics in the photo gallery for ideas.
"You become responsible, forever, for what you have tamed." -Antoine de Saint Exupery-