you likely won't get anything good in that price range new
EDIT: noticed the link above, that's a reasonable option if pcie is what you need

I'd try ebay or refurbished items off newegg
another option is using this opportunity to build a new computer

llano cpu (with integrated graphics that beat $50 cards) can be had for $80-$130 + motherboard $80 + memory $60
assuming the psu is recent that's all you'd need
of course intel is another option, their integrated graphics is pretty good on the i5 cpu's these days.
what are the exact specs of this system ?
pcie or agp connector ?