The bedroom ceiling drywall, one wall, and the bedroom carpet all had to be replaced.To be fair, the tenant had no access to the downstairs bedroom, but his negligence to let me know of the water leak in the upstairs kitchen led to extensive water damage.The insurance company said they estimated the damage to be $5,489.

I estimate that we've spent a few thousand in medical bills as a result.When we asked Fujitsu about the mold issue, the said that we should hire a contractor to come clean the units regularly.

Zillow also has a "z-estimate" for the range in rent you might expect for the property but it is not always accurate.

You must avoid the 2 most common mistakes, over estimating ARV, under estimating rehab costs.

A legitimate and reputable wholesaler has to be able to find a good deal, estimate rehab items, and cost, and know the exit strategy or investment return on the deal. 

Right now my model is buy cash under 75k (keeps holding costs low), rehab estimates around 20k all in assuming worst case, in markets that handle 130k resale. 

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookConsider checking out HUD homes for small multi's owner occupied gets first crack.Download BP’s newest book here some good due diligence in Chapter 10.

I have sent some LOI's to sellers based on the drive by and a worst case scenario estimate for rehab.

Does anyone have any suggestions for websites or other online resources that are good in determining rent estimates in different areas? 

I will get more estimates and I didn't think about the labor/material cost thing.