galaxy - Galactic extinction as a function of distance

You might want to have a look to the GALExtin models. The official site is still not finished (not even sure if it's still being developed), but you can access the original article here, and download the models here.

Here's a poster that provides a quick introduction.

Basically this is composed of two models of the Galaxy (one with spiral arms and one without) to which you give a (l, b) direction and a distance, and it gives you back the extinction.

It's a little bit old but perhaps it can be useful to you.

Also, the advice given by Rob is a good one: for such small distances perhaps the best thing to do is to assume zero extinction.