Or is it just studying your market and knowing the opportune time to offer 30k below list. 

Also, if you purchase a home at below market value, do you figure the rent ranges based on the purchase price or the true market or ARV?

Unfortunately, us REI's want to purchase as far below market value as possible.

One of the units was partially below grade, and water got in and ruined everything.  

Here are a few recommendations for you:Find and connect with other BP members that are in your area: http://www.biggerpockets.com/meet Set up keyword alerts to be notified of the topics that interest you: http://www.biggerpockets.com/alerts Read Beginner’s Guide: http://www.biggerpockets.com/real-estate-investing Check out BP Podcasts: http://www.biggerpockets.com/renewsblog/category/podcast/ If you wish to tag someone in the conversation on the forum, type @ followed by their name and then select the name of that person which should appear below the comments box.

It doesn't matter if you are young or old, totally new or need to build upon your experience.Yes, you have just announced a commitment to the thousands in this community about your seriousness regarding REI and have taken this bold step to affirm it.Your time on this site and with the BiggerPockets community will be well spent and can be financially rewarding if you so desire.You are here at the Forum, but, should raise your mouse to the top and explore the otherheadings displayed.Don't get overwhelmed by the massive amount of data archived on this site.Simply, bone up on the areas that you need to expand knowledge in such as, Forums,Marketplace, Learn, Network, Analyze, Resources.Feast on the Podcasts, #askbp Podcasts, blogs, webinars and the myriad of bookrecommendations.Also, you can review the quick links below to help solidify your grip on this site.http://www.biggerpockets.com/starthere Setting up Keyword Alerts How to Use @Mentions on BiggerPockets 25 Tips for Real Estate SuccessAfter becoming more knowledgeable and confident because of my above suggestions, take action to snag your first real estate investment deal if new or add to your existing holdings if you have prior experience.Don't get caught up in analysis paralysis.You must immerse yourself in the RE marketplace locally in your neighborhood or afar if the situation warrants it.Take calculated risks if needed and you shall be rewarded!"

Here are a few recommendations for you:Find and connect with other BP members that are in your area: http://www.biggerpockets.com/meet Set up keyword alerts to be notified of the topics that interest you: http://www.biggerpockets.com/alerts Read Beginner’s Guide: http://www.biggerpockets.com/real-estate-investing Check out BP Podcasts: http://www.biggerpockets.com/renewsblog/category/podcast/ If you wish to tag someone in the conversation on the forum, type @ followed by their name and then select the name of that person which should appear below the comments box.

A good site to use if you want to do your own is redfin.com When you run a search, filter the criteria and on the right side of the page it will list all the properties that match that, at the bottom of that list is an option to "download all" and you can export the file to a excel document and run a comp analysis

Ok, now that you have taken your initial step, below are some quick links to get engaged.http://www.biggerpockets.com/starthere http://www.biggerpockets.com/meet Setting up Keyword Alerts How to Use @Mentions on BiggerPockets 25 Tips for Real Estate SuccessREI can be very daunting, but, before you go searching for that 1st buy, please take a few minutes to bone up on the tips in link below.http://www.realestate.com/advice/buying-your-first-investment-property/

Here are a few recommendations for you:Find and connect with other BP members that are in your area: http://www.biggerpockets.com/meet Set up keyword alerts to be notified of the topics that interest you: http://www.biggerpockets.com/alerts Read Beginner’s Guide: http://www.biggerpockets.com/real-estate-investing Check out BP Podcasts: http://www.biggerpockets.com/renewsblog/category/podcast/ If you wish to tag someone in the conversation on the forum, type @ followed by their name and then select the name of that person which should appear below the comments box.