If you touch whatever the PC is laying on (if it's a laptop) or the case (if it's a tower), doesn't that discharge the static? If you want to go the grounded mat route, surely you only need a small piece (6" square) on the floor that you touch with one foot before touching your hardware? Ground the chair you sit on? Get an extra-long grounding strap and put it around your ankle?! Depending on the grounding of the PC, or lack of it, that could be the problem. You usually get a good spark if you are charged and the object is grounded. If everything is floating, often there is no discharge. My PC is not grounded and I never have static problems with it. If I'm working on the internals, I ground myself to the PC. We could be at any potential relative to ground but it doesn't matter providing we are the same.
Edit: Re your last comment, try borrowing things to see if they help. Runner rug, thin doormats, interlocking exercise or anti-fatigue mats (set of 6 for $12). There are plenty of home remedies of varying practicality (google the problem). Simple and effective is to increase humidity with a humidifier or plants. That may be limited by windows freezing over in very cold climates.
Edited by Nanobyte, 28 January 2013 - 02:07 PM.