A lot of people get custom bike frames, and customize what equipment is mounted on those frames, and how. That adds to the cost.
I wonder if a good fitter is just as important for bikes as for skates. I hope you visit lots of bike shops to see if something already feels right.
I never quite figured out what the optimal frame configuration is. It's not just the height of the seat that had to be right, but also the forward/backwards position of the seat relative to the wheels, handlebars, brake and shift controls, the height of the pedals above the ground, how far you have to lean forwards to put your hands on the handlebars or reach the brakes and gear shift, and some things I never understood about how well the bike balances, tracks and turns. (E.g., if you have to remove your hands from the wheels for a second or two, does it go straight? Do the pedals drag and catch if you lean into a turn? Is a lean enough to turn?) Also, how comfortable the seat is to sit and pedal on long term. Also, is there any way your pants (or skirt or dress, as appropriate) can get caught in the chain or gears? Is there anything to block dirt and grease and rain from the chain and tires from being thrown onto your clothing? How easily can you remove your feet from your pedals if you have to in a hurry? Is there a good way to mount a decent bike pump - little ones may take a size-able portion of an hour to use, and the little gas cylinders are bad news if you do it wrong the first time. Is there a good waterproof place to carry your tools, repair instructions, lock/cable and whatever you need with you on the trip? Lights and horn are good. For people who get lost like me, a GPS would be fantastic. How hard is it to lock all components securely? Some of these things are somewhat adjustable or interchangeable, some not.
I'm pretty sure that I liked a different configuration best when I was sitting and standing tall on the pedals. Also that everything about the feel changed when I went up a hill. I like having a very low gear, and a very high gear, but maybe that's because I was never a great athlete.
When I bought my Viscount Sebring ten speed half a zillion years ago, the user manual told me how to balance the wheels, adjust and replace the brakes, adjust and lube the derailers, chain, and cables, how to lube and replace the wheel bearings, how to adjust seat height and forward position, and the configuration of the handlebars, how to repair and change tires on the road, etc. I knew nothing about tools, but I had no problem following the simple well written and illustrated directions.
I'm told that as the number of gears has increased, "click" derailers have taken over, and custom tools have become more common, fewer people can maintain their own bikes. My local REI charges more for a "deluxe" bike "tune-up" than I spent for my ten speed, even allowing for inflation. In addition, most bikes you buy from the store are custom configured to some extant - there might be one set of manuals for the various components of the gear system, another for the brake system, etc.
But it is worth while to look at the available documentation to see if you can do the most common repairs on the road. Find out from the shop what it would cost to get the tools and documentation to get the chain back on the gears, re-adjust the gears and brakes to the extant that they work reasonably well if something goes wrong, and replace and re-inflate the tires. All those are often needed unexpectedly on the road, so it may be worth getting the tools and practicing at home.
The information clarity and availability, and the tools required, varies substantially according to the equipment on the particular bike.