Woohoo! I got into pinball a year ago...6 machines later...

This may not be the right advice you YOU.....but I'm obsessive and did my homework when I became addicted so here's my advice:

If you buy them all right now, they will not be the right machines.

If you're anxious....take a little of that coin and do a 2 day vegas trip. And get deep in The Pinball Hall of Fame. Within 3 months of that seek out anything in the top 30-40 you haven't played that entices you.

Then...you'll make the right decision.

If it were my money and I already had the AC/DC (GREAT CHOICE!)...and knowing older machines require more maintenance....I'd add:

STLE - no matter who comes over this get's the most return love. It's sexy and addictive. Wherever I go...it holds up.
Creature from Black Lagoon
TBL - only if theme is right for you. This is a dream pin IMO....might just be me though.
MET (PRO or LE)
TRON (PRO or LE)

Yeah....it
might be more than 19K....but I told myself 1 machine. So a budget is laughable to me, because over the years you'll adjust and evolve and if you have room for 5 machines and are willing to spend 19K...I'm guessing you're willing to fill those 5 slots with whatever give you the most love in the end. Good luck...nothing like new love!