[ddharriman]

For that diference in price and with the tamrom 17-50 f/2.8, my advice is to go with the K5.

[Des]

I have reached to this point:

Pentax K5 + Tamron 17-50 f/2.8 Di (used/mint) -> 400$
Pentax KS2 + 18-50 WR (new) -> 600$

Because of the price difference, I think I'd get the K5, as I would be able to buy a tripod and another lens with the 200$ that I save not buying the KS2. What do you think? Is it a correct decision or would you get the KS2 no matter the price?

I had assumed we were talking about roughly the same price. With such a price differential, and on a tight budget, the K-5 is a very attractive package - yes with a $600 overall budget, that's a better buy IMO.

The Tamron lens is not WR of course, but it has many fans: see the reviews, including a PF staff review: Tamron AF 17-50mm F2.8 XR LD Aspherical IF SP Di II Lens Reviews - Tamron Lenses - Pentax Lens Review Database

A tripod is essential for your needs. You might also want to leave room in the budget for a flash too - you can get something quite reasonable for say $80-100, maybe less. If there is only about $100 left for another lens, consider the DA-L 55-300 (or DA 55-300 if one turns up for the price) - it's about the best value for money lens available, and it will round your kit well as a starter combination.