There is no problem obtaining iso-octane - it's the pain of paying for it. Note that reagent grade isn't good enough. It needs to be spectrographic grade. As you are familiar with the procedure you may have noted that triple distilled gasoline from the pump is acceptable but I'm not distilling any gasoline in my lab! I also wanted to call your attention to the fact that you can't just dump it down the drain when you are finished with it. You have to have a proper disposal arrangement in place which is more expense.
There is a procedure for alpha and beta acids which is similar (same gear - shaker, UV spec) to what you do for the IBU's except that the hops themselves are extracted with toluene, the extract is diluted with methanol and absorption measured at two UV wavelengths.
Distillation is fine but time consuming (that's why I asked about how you would value your labor). Then how do you measure the distillate? A hydrometer isn't going to cut it. You can do it with a pycnometer and balance but that is also very time consuming. With a pycnometer I'd estimate 6-8 hrs for an analysis. With a densitometer you can cut that in half but a densitometer is a pretty expensive piece of gear.
What I'm getting at overall is that you need to add up the cost of the pipets, the petrol, the hydrochloric acid, the centrifuge tubes, the cuvets (if you use disposables and they are great for the color measurement), the depreciation on all the equipment and what you want to pay yourself per hour in setting a price. I expect that price will be more than most homebrewers want to pay unless you are willing to work for less than minimum wage. I do know a guy who is doing this (and making a living at it) but his customers are craft, not home, brewers.