Shopping recommendations are off topic as per the FAQ, so we can't tell you what to purchase. That said, considering the slots you have available, here are a large number of $30 PCI-E 1gb cards. I'm not recommending any one of them (although there is nothing wrong with any of them), I am simply pointing out that your assumption that there are no sub $50 options available is incorrect. I know.. I know. You said you were hoping there were some $25 options. Well, what about some $20 options?
At this point, if you get the urge to get picky and say that you don't like this particular chipset, or you don't like that partcular name brand... or you were hoping for more video memory, etc... resist that urge.
Now that you have multiple inexpensive options to you...
Would I need an additional PCI-E card?
You shouldn't, since your motherboard has an integrated video controller with Multi-VGA output support : HDMI/DVI/RGB ports. You would simply make sure that your integrated video was enabled in the BIOS, and that it was not set to be your primary. Then, Windows should detect both your video card, and the integrated video, and allow you to connect three monitors without an issue.
How old should the graphics card be max?
Old enough (or young enough) to have drivers available for the operating system you choose to use. Other than that, you can get one as old as you like within that parameter.