Might sounds simplistic but did he make any mention of what he might be looking for out of the properties ?

I'm not in real estate full time in LA but I can't imagine there's a house or income property anywhere in LA that I can buy for $300,000 that will generate $3,900 in gross rent....I totally realize this is a simplistic approach and I have more vacancy and maintenance issues in Barstow...however, if you want to help me crunch numbers of long term value of the $300,000 in LA vs. the $300,000 in Barstow I'd be interested to see how that would play out...actually, as I write this out, I'm going to do a quick analysis also based on rents in LA of $2,000 per month for a $300,000 investment with rents going up 3% per year and appreciation of 5%...and compare to $300,000 in Barstow with rents going up 2% per year and appreciation of 2.5%...just for fun.

I'm just getting started in REI so this might be a simplistic question, but here goes. 

TIM wants to be bought out for 300K, but my aunt wants to stay 50/50 with US NOW.What is the simplist way to finance and buy out Tim, but keep my aunt on the mortgage?

I don't really know how to explain this simply, as you need to understand (even at a simplistic level) how lenders operate.

I'm a newb myself, but assuming your comps and research are correct, my simplistic take on this would be:Option A: Find out what repairs are needed for a flip.

I know this sounds simplistic but everything begins with a plan.

I get that this is overly simplistic, but if I'm out of pocket $200/month to get $466/mo in equity thats not horrible, understand this is not liquid and if the cash is important then this is not ideal. 

I’m also in talks with Simplist and OwnUp.

It's a horribly simplistic way to look at "value" but if they know what properties are generally trading at then it's at least a starting point.