Potential first wholesale deal? Need help!

[Dan Miller]

I've found a few foreclosure properties in the same neighborhood and am trying to figure out the ARV. A realtor has sent me recent comps, all of which are from Sept through Jan. '08. For this subdivision, they range from 430k to 580k. I'll assume the 580k property is an outlier, as it looks like it has a new addition, unlike the others. If I ignore the top and bottom comps, the range is still large: 440k to 530k, with a median of 500k.

My approach is to determining maximum offer is to take 70% of the ARV (from the comps) and then subtract my wholesale fee and rehab costs. In this case, I'm not clear as to what the ARV should be. There's such a large range (90k), with the median around 500k. Even reading the notes from the comps, there doesn't seem to be much discernable difference b/w a 440k and a 530k. Assuming 500k ARV vs. 440k could result in me overpaying big time. Just not sure what to do. How do I handle this? What should I use as the ARV?

Comps:

9/27/07 $430,000
11/2/07 $440,000
10/31/07 $499,000
9/14/07 $494,000
11/8/07 $503,000
11/9/07 $510,000
10/19/07 $530,000
10/24/07 $580,000
12/20/07 $515,000

Thanks,
Dan