I agree you need to answer the questions posed by timlub, mhsmith and gdnrbob above before beginning your purchases. Once you do that, I would start with determining which speakers you want since they are arguably the biggest influence on how your system will sound and the speakers will also determine the appropriate amplification to best drive them.
The best way to determine what speakers you want is to do what gdnrbob suggested; listen to as many speakers as you can while also identifying the type of speaker you generally like the sound of best or least - dynamic cone, planar, horn, electrostatic, etc. - so you can whittle down the abundance of choices to a smaller more manageable list of candidates.
Closely related to speaker selection is whether you need or want to use subwoofers in your new system. Based on my personal experiences over the past 40 years, I consider the best approach in any room is to first get the bass performance to your preference so that the sound has a solid foundation and then progress to attaining good performance on all the frequencies above the bass.
Typically, it is considered more difficult, by most who have attempted it, to get good bass response in any given room than it is to get good performance on frequencies above the bass in any given room. My knowledge has developed to the level that I've been able to attain good performance in my room for the entire audible frequency range and I believe I can assist mhsmith and others in achieving similar results in their rooms.
I understand, however, that you can't currently afford to buy a complete system all at once. If you'd like to get your new system up and running as soon as possible, you may need to deviate from a predetermined optimum sequence of acquiring the components. I'm referring to things such as possibly delaying the purchase of your planned speakers and using your smaller B&W speakers instead so that at least you have some speakers to use while you save for your desired ones.
Tim
onc
