I always thought pple had problems getting Pentax lenses in SG...
But are they expensive?
Not really. its just that unlike the other makes where you can find in many shops, only a select few shops carry Pentax lenses and since you know where they are (from this forum), there's really no issue.
As for prices, what good lenses are not expensive?
At least you're not overpaying like C lenses. My C-owner friend tells me C stuff in Singapre sells up to 20% more expensive than compared with other countries, likely due to monopoly...