I used the k20d with that exact attitude, with only the kit lens. It was a great experience. IQ was great, I learned a lot about photography, and for the longest time I had no idea what I would even need to buy next.
Then, I bought a 28mm prime, f2.8. I was struggling with the kit in lower light (exacerbated by the k20d's sub-par ISO 3200). The increase in IQ was huge... and the price was not exactly crippling considering the cost of the camera itself!
Flash forward about 1.5 years later, and I have a pretty good case of LBA. I temper my LBA in 2 ways... I buy AND sell, and do so with used items, so the lenses work out to be "free". It does not always work... I do have some issues offloading some of them (have not played with EBAY yet). Overall, though, I do not think I have sunk an exorbitant amount of money into products, because they all have reasonable or equal resale value. I really think that a DSLR owner is missing the point of an SLR without playing with different lenses. The camera itself is a disposable thing, but the lenses last forever (hopefully), and are the source of the image quality. It was never so obvious to me, as to when I bought a cheap 80-200 f4.5 Takumar Bayonet zoom. It's a good lens, for 30 bucks. But overall it just had none of the qualities of my 50's or 28, or my kit lens. The glass really matters.
Pentax is a fun system (I imagine Nikon, Oly, and Panasonic are as well) due to the long heritage of very affordable lenses with great image quality. Owning many lenses does not need to be expensive.
Some notable examples:
K55 1.8 - 60 dollars.
A50 1.7 - 50 dollars.
A28 2.8 - 100 dollars.
F70-210 - 50 dollars.
Those 4 lenses come out to the price of a used FA 50... and give one all sorts of fun tools to play with, learn about, and cherish.
The other nice thing about this strategy is that you can sell off individuals that do not work for you. If I every decided that the A 50 1.7 was not getting much use, I would be able to sell it for what I paid (easily) and dedicate that money to some other aspect of my life.
The DA*s and FA ltds. are out of reach for many... but by the same token, I would think that the Tamron 17-50 or 28-75 are very affordable to someone wiling to spend 600-700 on a camera body, and they will really take your photography to new places
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PS: Tony, I love that shot of the clock!