It's never a good day when something goes wrong on a computer. Whether the video card goes out, there's a virus, or more, costs can be something relatively cheap to something very costly. The observations below are based on research from retail and repair stores, both national and local to the author, as well as user comments and experiences.
Please note that pricing listed can vary depending on where a user lives. The best thing is to call your local repair store for an estimate.
I am a PC person and as a PC owner, I of course think that repairing a PC is much cheaper than that of a Mac. I've had to replace parts, as well as taking my computer in when something needed replacing that I couldn't do. Laptops are a bit different than a desktop, as parts are smaller and sometimes may require a professional.
Looking at repair at the local level, pricing does vary. For instance, one repair place charges $75/hr for normal issues, like updating a laptop. Other places charge from $85 and up. At the local Best Buy, any hardware repair can range from $29.99 and up.
Mac repair cost was a bit harder to come by, especially from the elusive Apple Store. Apple computers are built differently from standard PCs, and most of their components can only be bought from an Apple retailer. By asking around, I got some answers on price, or at least some estimates. At least from the Apple store, screen replacements can be from $700 to $800, while hard drive replacement was about $1,000 and a logic board about $1,500.
This is of course from users who experienced issues and took their Macs to their Apple store. Again, these prices may vary depending on where you live. Online prices seemed to be cheaper, with LCD screen repair at about $199. At Best Buy, it seems their PC and Mac prices are the same, though you may want to call or walk in to see an actual estimate.