My advice: get one or more primes. Why? For $300, there are a number of very high quality prime lenses available, particularly on Pentax with its extreme backwards compatibility, and so you're likely to find a pro-quality lens that you'll keep and use for years. On the other hand, at that price point it is very difficult to find a high-quality zoom.

You note that you have no prime experience, so perhaps it's also a good way to expand your repertoire. It's often fun to work under more constraints, and prime lenses go down to f/1.4 rather than f/2.8 which is the limit on all but the most exotic zooms; those two extra stops can mean a lot.

Regarding your four suggestions:

• Don't bother with the zooms. They will be low quality.
• An 8mm fisheye is for full-frame. On 1.5x crop, you'll have kind of the worst of both worlds: a cropped field of view and heavy fisheye distortion. Now, a fisheye is certainly an interesting and very fun lens, though quite specialized. IMO it's a worthwhile component of any kit, but not the best second lens. If you do choose a fisheye, I've used the DA 10-17 and it's very nice, though slightly above your price point new.
• The DA 35mm would be a fine choice, but there's nothing particularly special about it that would merit waiting.

Where to go from here:

• Browse around the PentaxForums.com lens database. This gives data and reviews on nearly every Pentax lens that ever existed.
• Consider used. This is a good way to get a great lens cheaply (or maybe even two).
  • keh.com is highly reputable and I've had excellent luck with them; they back their used sales with a short warranty.
  • Here is one of many Pentax lens compatibility charts.
  • If you have some patience, consider a manual focus or even screwmount lens. You can get superb glass for very cheap; for example, this 50mm SMC Takumar costs only $70 and I can assure you those Takumars are truly remarkable pieces of kit. (Note that with screwmount, you need an adapter and it's important to get a high-quality one.)