You'll definitely do better if you're willing to split the range up into 2 lenses.
The Tamron 17-50/2.8 and Pentax DA*50-135/2.8 would be your best bet (both purchased used, of course). It may go slightly above your budget, but should be very close (at least based on approximate/estimated Marketplace final selling prices here and the currency conversion rate). This will cover the whole range with
very high quality. They're also fast, and eliminate the need for primes in most situations (unless you
really want to expand your budget!). These 2 lenses combined with your K-30 is almost certainly the best quality you can get for the money from any brand. Take a look at DA*50-135 images here:
PENTAX : Select a PENTAX interchangeable lens camera or a lens model PENTAX : Select a PENTAX interchangeable lens camera or a lens model
You're actually not "dreaming" when thinking you can get it right the first time. With your stated budget
Originally posted by JPE In response to Special K, AUD $800-1000 seems about right as a budget.
you can actually do it if you're willing to go to the top end or slightly over.
For macro use you should get another lens. The good news is a number of good macros are available in the $100-ish range. My choice is the Cosina 100/3.5, but there are a number of others (especially older MF lenses, including Pentax) as well. After you cover your basic range of 17-135mm (which should cover about 80-90% of your shots) you can worry about the macro or any primes you might need. I dare you to start with just one of these two lenses and compare it to the Sigma 28-80. I don't think you'll need any more convincing.
So, believe it or not, I think it can be simple.