I assume you meant ordinary in terms of Apple PCs, which is still expensive; Apple prices even their low-end stuff quite high. MacBooks start at $999, and you usually have to at least get some hardware upgrades if you plan to actually use it for anything.
If, on the other hand, you meant you were using a PC, I should probably let you know that running OS X on anything except an Apple-labeled computer is illegal according to the
OS X End User License Agreement. By using OS X, you are licensed to use their product on one Apple-labeled computer (Section 2, "Permitted License Uses and Restrictions," subsection A: Single Use), unless you purchased a "family pack," in which case you can install on five Apple-labeled computers. Just an FYI.