Vancidium is way to expensive to make buying it profitable. At least I think so, I have actually never crafted an advanced bionic in any of my playthroughs to be honest.

The trick is to research up to basic (middle tier) bionics and then mass produce them for sale to the prostesis traders and then using that money to just outright buy the advanced bionics in return.

I say this because regular bionics don't require vancidium, which is horribly broken econmics-wise. Buying the finished advanced bionic items is far, far cheaper than buying the raw materials. You can also try make them yourself, but it is absurdly time consuming and I don't recommend trying to do it unless you have mods for "deep core drilling" (so that you can actually get the amount of materials needed) and the advanced robots mod (tier 3 crafting bots can make it for you).

Otherwise, like I said, you're better off just building a dozen regular bionic arms - which is relatively cheap & easy - and then when the prostesis trader shows up swap those for one advanced one. This is actually easier & less time consuming than trying to make advanced components.

Along the way be sure to do this also: Take your regular bionics and outfit all your non-prostophobe colonists with them. You can always swap them out for advanced ones later once you find them and will get the original parts back after surgery. It's not the top tier of bonuses but it's a heck of a start.