A big budget or not Newcastle should have no problem in building their squad. They should not rush it. Let it follow due process. hey can just add three or four players to their squad and sell some players that are surplus to requirement. They should take the process slow or they might miss it and see themselves spending unnecessary just to stay relevant.
If you have zero or small budget for transfer, you will have more difficulties to build up your squad and will be less competitive than squads of rich clubs. You can play well in one season but in three or five seasons, you will be worse than other rich clubs with bigger transfer budgets.
They should just try to get quality squad depth and get players that can make them in the top four. They can also play to win other trophies like the caraboa cup and FA cup but the league and champions league is a little beyond them at this point.
They had good ending in this season and they will need to have good plan for transfers to buy good players who match with their tactics and won't break united team-mateship in their club.
Winning titles is good because it will help them to have feelings of being champions. However, they must focus on two biggest competitions, Premier League and Champions League. They must play well in Premier League to join Champions League regularly and get chances to play against strongest teams in Europe. They will learn a lot from Champions League.