Hello nandus,
Hopefully you already did research about cpap and sleep apnea? beacuse the preassure of cpap is normally set by a sleep lab technician after doing an overnight sleep test. I am not aware of any supplier in Qatar. But once, I have bought filters, mask from http://www.cpap.com . They ship internationally. If you have budget, please buy the best one. Also do some reasech about the mask they come different sizes, getting the right sized mask is very tricky if you have smaller face or chin. You can also do a reaserch in Amazon.com just type cpap.

If you have more questions feel free to ask.

Good luck.