Intermission: My Series 1-16 Unopened Pack Availability Guide
Disclaimer: these are just my personal impressions based on looking for packs for the last decade
VERY HARD TO FIND:
1st Series, 5th Series yellow (85-fold only), 11th Series green
FAIRLY HARD TO FIND:
2nd Series, 3rd Series red, 5th Series yellow (21-fold), 8th Series blue, 10th Series (21-fold only),
11th Series yellow, 16th Series
AVAILABLE BUT NOT COMMON:
3rd Series yellow, 4th Series, 5th Series blue, 9th Series (21-fold only), 13th Series
FAIRLY COMMON:
6th Series (except 21-fold no ad), 15th Series
VERY COMMON:
6th Series (21-fold no ad), all 7th Series, 8th Series orange, 9th series (85-fold), 10th Series (85-fold), 12th Series, 14th Series