Since 'Availability is an issue' where you live; and your cashflow is limited, I would recommend buying a bike that fits 80%-90% of your requirements and modifying from there.

From my experience and what I've read here, unless it's a bespoke, boutique bike, doing a full frame-up build will cost 30-50% more than the identical-spec bike bought 'off the rack'

Also, do you have a specific ride or trip you want to take this bike on? 'I want to ride Alaska to California' or 'spend the summer sightseeing in Europe' or even; 'I want a bike to replace my car'
If you can tell us what you want to do, we can give you a better idea of which direction to start.