The same condo layout for other buildings within a 1-2 block radius have sold for $550,000 - $599,000.

Philly is a block by block city that can change pretty dramatically.

If someone lists their property for sale on the open market, then we pursue the property (Within reason) so that other people can’t block our assemblage.We are using different entities to hold  title to the properties.If we purchase enough of the surrounding property, we would like to approach the city and rezone the land from office to mixed-use (Residential over retail).Any thoughts or strategies you have employed to make an assemblage successful?

Look at other houses on the block.

It'll be more expensive, but I use an exterminator that blocks all the entries to a property and gives a 1-year guarantee.

I had to block him to stop it.

Screen your tenants, have good property management in place, hire a Realtor who can assess homes block by block & you should be in good shape. 

My aunt owns a building 2 blocks away from it so she has some knowledge regarding the building and also working with a realtor but we are currently getting more info like building history and etc to see if this is a situation of the owner wanting to dump it or if he is just too old now to deal with it anymore .

Starting part-time is great because it takes months to learn the basics AND get your business started.Time blocking will be extremely important.

In LA, surprisingly, duplexes are often priced comparable to the house two blocks away when they you're getting two homes.