it's better to spend at least 1k to start off rather than upgrading. You will feel better with a bike that works very smooth out of the box and one that'll stay smooth for a while. Lower level components have a greater chance to get out of tune and would require more tuning in the long run. If you compare shifting between Sora and Ultegra you will notice a difference, ultegra is a lot quieter and smoother and has the ability to micro adjust the front derailleur to prevent chain rub in all gear combinations. You can make lower level components run well but it'll just take a lot more work.

But with the bike just don't look at the name but just try them all out and pick whichever one fits you best. A bike that doesn't fit will cost you even more in the long run.