If you're set for buying a PC at microcenter online, you can just use the website to select from "video connectors" to pick the config you want. Unfortunately, as you guessed, I didn't see any that were near your price range pre-configured. I might call the store first and ask them. You can probably find a decent dual monitor card to add on for $50ish, but you will have to know what PC you're getting first so you get the correct card to match.

Would you ever buy used? If so you could likely find a business refurb computer that might work, especially if speed/gaming/power was not a big deal for you. One other good option would be a used business laptop with a docking station, as dual monitor setups are very common with a corporate laptop setup. Let me know if you want to look in that direction, I might have something.

One other thought - with black friday coming up, you may want to wait a little bit longer. I wouldn't wait in line or anything, but there are almost certainly going to be good deals online.