http://www.ebay.com/itm/COMBO-DP45S...513332?hash=item3d1ba09334:g:4qMAAOSwcL5XM72yAssuming you're buying new, a case + psu + ram + mobo + disk are gonna run you $150-200 at the cheapest no matter what. You might find some clearance barebones kit for $100. But there's no way you build an entire PC that can run any modern games better than his existing machine for $150.
You might scrap his current PC assuming the case can fit a new card. Given that he's running DDR1 in a 2004 machine, he probably has some ancient 300w psu that's degraded down to 200w by now. If he wants to buy a graphics card that can run anything modern at all, a 200w is not going to cut it. And most likely his current disk is NOT sata, so you can't reuse that. I don't see how you came up with this $150-200. Maybe if you're buying off the shelf at walmart, but that isn't considered building.
There's also no way a $200 PC is going to last long enough to make it worth buying in the first place. That puts him in the same boat he's already in.