The reason i ask is im probably getting a d80 or d200 soon, and i'm looking to get a high quality starter lens but dont want the jump in price that the 2.8's cause. Might just end up going with a couple primes instead.
You can get lenses like the 3.5-5.6 in most ranges...and they aren't horrible.
However...there are some 2.8 lenses that aren't TOO expensive.
There is no point in making a cheap zoom a constant f/4...
cause it'd be cheap as hell to make up for the fact it's f/4
Making a fast lens and making a zoom a constant aperture both cost money...so you can't have good/fast/cheap in the same zoom lens.
Now...if you want a starter lens, I'm sure you will be fine with a variable maximum aperture in most cases.