Go to
eBay, look under "Computers and Networking", then under "Desktop and Laptop Components", under "Video Cards for Desktop PC", select "Buy It Now" (don't worry; you won't buy anything, it just means to show only items that you can buy, instead of bid on.) Sort the list by "Price - lowest first" from the drop-down box on the top right.
Here, you can find some cheap cards, such as
"NEW GeFORCE FX5700 LE 128MB TVOUT W/DVI AGP NVIDIA CARD" for about $45.00 after shipping. Find one that is pretty good, for a price you think your parents might go for, and that your computer supports. Also, make sure that the seller rating is good (I'd say 98% or above, with more than 500 ratings.) If you are not sure if your computer will take the card, or not sure if it's a good card, ask - one of us will probably respond. To find out what kind of computer you have, get
CPU-Z and run that, it will tell you - you want to see if your motherboard supports AGP, and if so, what version. You can tell this by looking up the specs of your computer's motherboard on its manufacturer's website, using the model number.
Of course, your parents might not want to upgrade the computer... but I suppose it's worth a shot. What do you think?