Well, as I didn't know what to do with my money I started upgrading Pillars and Pendulums - only 21 upped cards still missing for a complete 15-15 collection.
Missing rares:
0+3 Lobo, 3+0 Stiletto, 3+0 Pharaoh, 2+0 Morning Star, 4+4 Trident, 1+0 Druidic Staff, 0+1 Titan, 0+2 Arsenic, 2+2 Discord, 5 SoR (and some unupped Shards and Relics, but I wouldn't count those)
I really should start farming for rares, but farming FG is so much more fun - perhaps T500 will help to find the motivation.
I've finally upped 15+15 Pillars and Pendulums (or more) each - so I'm only missing some rares for an entry in the list (it will be a bit harder to get the unupped ones with Arena).
Missing Rares:
0+3 Lobo, 3+0 Stiletto, 3+0 Pharaoh, 2+0 Morning Star, 4+4 Trident, 0+1 Titan, 0+2 Discord, 6+0 SoR (should be nearly impossible to get them unupped now), 1+0 SoG, 0+3 Relic
Question: Do unupped Shards (especially SoRs) and (upped) Relics count?
edit: Score 351,257