Just use the kit lens.
If you want an upgrade, I hear the Sigma 17-70mm F/2.8-4.5 is highly regarded agmonst users on DPreview.
Why not get some of Pentax's classic MF primes?
I have a Pentax-M 135mm F/3.5 I can sell to you for $40. It works really well as a small, portable telephoto, and it's a bargain at 4 hamiltons!