DIY Weathering powders

So I've been really interested in getting some of the weathering powders that seem to be the rage lately. Unfortunately there aren't any local retailers that carry them, and shipping to Canada has killed any other deals. So, I pulled some old ideas out of my scale model history and decided to give soft pastels a shot. Note, these are not oil pastels, and are very similar to chalk (in consistency). Anyway, I picked up the cheapest package at my local Michael's craft store (with a 40% off coupon of course) and gave it a shot. Here are some pictures of my results. No black magic here... I just scraped the powder with the edge of an exacto knife, applied it with a big brush and used mineral spirits to wet it after.

The results are ok, but I think that's partly due to the lack of colour options. I'll keep experimenting and let you know.