@Mike R. The simple answer to your question is not, should you buy at full retail, it should be what is the position in the current cycle that warrants full retail? Let me explain. ALL property markets operate in cycles. Each cycle has a top and a bottom. Both the top and the bottom can only ever be clearly seen after you have passed them. In other words they are not known until after the event. However, with due diligence and some knowledge and a lot of work you can learn to read the indicators of where in the current cycle a market is sitting at and therefore make an educated guess of where it might lead to. There are many posts on BP covering this topic, so research those to get the basics of understanding property cycles.
Now, imagine the property you are considering buying is in a market that is on the upswing in its cycle. That is to say the property cycle is rising and with rising cycles come increasing prices. Demand is rising whilst supply is falling causing an increase in prices. In this instance it is fair to say that property will sell at or near its full, CURRENT, retail value. If you can find sub retail values in these markets you stand to make even better profits moving forward.
Now imagine that the market you are looking at is at the top of its cycle. Again, prices are high and demand is higher than supply so property sells at its full retail and in many cases above full retail. In this scenario there is only really one place prices can go, and that is down. Cycles go up and down and when. like being on a roller coaster, you are at the top, the next stage is down. Prices fall and you lose equity.
Note, neither of these scenarios should have any immediate bearing on cash flows. Cash flows are an object of return on equity. in other words, if you paid cash for your property then it will no doubt cash flow very nicely. If you are highly geared then the cash flows may not be so good.
So, the answer to your question is, "what is the purpose of your investment"? If you are buying at or near the bottom of a cycle and you understand this then you may pay full retail and have poor cash flow by looking for the upcoming growth in the market. If you look at @Account Closed's comments he clearly shows that he would have bought his properties at or near the bottom of the cycle. He was investing to make capital gains, not short term cash flows. I say short term because rental increases always follow rising prices. I say follow, because rental returns are a factor of yield for an investor and the greater the value of the asset the greater the cash yields should be to warrant the investment in the first place. Bob therefore was playing the game ahead of time. He was buying low priced property in an increasing market that he knows will increase in rental yields. He would then, as he no doubt does, increase his borrowings from the increased equity and cash flows to free up capital to go again. Thereby reducing his initial investment in the property and raising his IRR, plus having the funds to invest in other deals.
If, on the other hand you are buying for cash flow only then you are only partly playing the game and missing where the real money is. The real money is understanding investment cycles, in this case property cycles. Buy low sell high. Or, buy low, refinance high, buy low again, repeat. Follow Bob's lead because when a guy spends most of his working life as a professional property appraiser as he did, from what I know of him, you would be wise to acknowledge that he understands market cycles. He knows when to buy and when not to buy.
Would I pay full retail for a property? Absolutely, in the right market conditions. Would I prefer to get it below full retail? Absolutely. But I invest to make money and making money is what it is all about. Knowing your market and where it sits in its current cycle will make these decisions easier for you to make moving forward. If you do not understand your market and its cycles then these decisions will always be difficult to make.
Good luck on your journey!