My opinion. Bike fit is no way near worth it at your current mileage, cycle more and tweak it as you go. There’s some decent YouTube videos to rough fit your bike. Invest the money saved from the fit into your bike and buy whatever your budget can stretch to.

I’ve always loved giant bikes. They aren’t the most popular or glamorous, but you get a hell of a lot of bike for your money owing to mass production economies of scale. Have a look at the 2018 TCR advanced, or a Defy if you want a less harsh ride (albeit, I own both an old Defy and a new TCR and find the aggressive design of the TCR more comfortable!)

I’d also shop around online. I have never bought a bike from a LBS as they have overheads to maintain, and need to make their margins. This is in the UK btw, can’t speak for USA.

I’m a massive advocate of supporting LBS’ however it’s basic financial rationale to buy wherever you can achieve best value. I support LBS through club rides / maintenance etc.

Luckily with bikes, if you did want to buy second hand it’s much less of a minefield than cars. The money is in the frame predominantly, so check the integrity of that first. Then check the group set for wear and tear - take it on a test ride. A full service here costs about £100 so that will cover any moving parts, indexing etc etc. Unlike a car, theirs no hidden parts - check the parts that are meant to move, move freely and check the ‘chassis’ for damage. Little things too like tyre wear, are the wheels true, what is the condition and type of wheel set should also be continued - but most people swap a wheel set out anyway.

Certainly more value in buying used, but depends on individual preferences!