More specifically, the owner and I would agree on a sales amount (165k), I would finance & complete the renovations along with carrying cost (estimate $15k) , and then sell the property at a higher amount (est $215k) ultimately giving the owner a portion of the profits (20-25%?).

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookLocate and attend 3 different local REIA club meetings great place to meet people gather resources and info.

I've seen people estimating full gut rehabs to be $50 - $100 per sq ft.

With that said can anybody, "loosely" estimate how many properties I would have to sell or buy and hold in order to reach that goal?

You could also go hard money, but just make sure you find rock solid deal with plenty of room since the first one will potentially be hard to estimate rehab costs. 

ARV will be 150k, getting it for 85- 25 of repairs estimated.

It's the agents way of saying that there is something so screwed up with the house that no institutional lender will lend on it, or the seller is motivated primarily by speed.Regardless, you will want an inspection to look for this screwed up thing and solid estimates for repair cost. 

Im still at the point where I am trying to accumulate as much debt as I can, but in a few years I believe I will have enough debt and will shift strategy.

I have to admit I am intrigued by doing this entire flip without seeing the property because that would allow me to fully utilizing my marketing abilities to go well beyond my current city if I can outsource every step of this process. 2 weeks in and we have an assignable contract with 40K in estimated equity.

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookGood luckPaul