There are test kits for lead. If you're not sanding the paint, you're fine. The only realistic danger with lead is if you have flaking paint and kids. Apparently, lead paint flakes taste sweet to kids. Yum! Better than corn flakes.
Given that type of a price drop, I'd check on a couple of things:
1. How much will it cost if you have an asbestos abatement company remove it, and how much will it cost for new siding?
2. What's the area like, as far as permits and stuff? In my area, if your entire house was asbestos shingles, no one would give two shits if you decided to carefully remove them yourself. My neighbor's is, and we've been expecting them to do this for a few years. When we cleaned our barn years ago, we found a huge pile of leftover asbestos shingles that match the side of their house - checked to see if they wanted them, they didn't, so just filled a couple boxes and took them to the landfill. Is it a job you can do yourself? Also, if it is, then you can probably install the vinyl siding yourself - 90% of the work is incredibly easy. Maybe even hire a person to do the trim around the windows, then do all the siding yourself.