well,,, zooms are better for single lens gig,  but fast zooms are expensive, one choice that you can find a clean copy at around 300 dollars is a 35-70 2.8, but it requires a drive for the focus.  so,, does a d5000 support the older afs lens? 
Looked it up, and turns out the D5000 does not have an internal motor, so maybe just a couple of 1.8 primes such as say 200 dollar 35 1.8 and the 50 mm, but you will be over the budget.