Quoted from thall17:Should you always buy Souvenir's?
You should buy them if they are associated with a city, like Nashville & the belt buckle. You get bonus points for those after you've completed the city. You can sell them in Albuquerque but since the multiplier applies to the bonus points it's usually better to keep them.
This table is the free table of the month on the pinball arcade app, lots of good tips and instructions on meeting the goals.