Mika, I truly can't remember how common (or uncommon) it is with sparaxis in individual colours, but as all of this got me thinking of UK nurseries and their often spectacular assortment of plants and various bulbs I remembered kevockgarden:
http://www.kevockgarden.co.uk/...
Not sure if you know about them or not, but in their catalogue last year they sold sparaxis in these colours:
Sparaxis 'Bright Star' pack of 70 bulbs £11.00
White stars with yellow centres, purple and white on the outside.
Sparaxis 'Moonlight' pack of 70 bulbs £11.00
Starry flowers, white with pinkish red markings inside and outside.
Sparaxis 'Skyline' pack of 70 bulbs £11.00
Very pale pink with a prominent dark red zone at the centre.
Sparaxis 'Sunshine' pack of 70 bulbs £11.00
White flowers, shaded pink, with red and yellow centres.
It wont let me post link directly to the old catalogue, but you'll find a link to it, if you first click bulbs on the left side menu.
Obviously no guarantee that they will be available when the new catalogue is published in January. On the other hand they may have even more cultivars
. In any case I think you might enjoy browsing their selection. Some of the packages are a bit big, but the selection is superb. Please note that I have never ordered from them, so don't know how well behaved they are!