G'day RSC,
As the other lads have mentioned, you'd be tracking down thousands of carts. In my case, I've attacked it this way, keeping it very simple and alot cheaper.
- I'm a player, hence simply want to have a nice, large collection of carts to choose from and enjoy on original hardware. So CARTS ONLY, no boxed copies. I use these .. http://www.retroprotection.com/Atari-2600-Cartridge-protectors_c261.htm for protection and neat cart stacking
- I'm down at the bottom corner of the globe (Australia), so I'm collecting PAL only, to match my PAL 'Vader'.
- As I'm a player, I only need one copy of a cart, hence No Label Variants.
- For Manuals, I have a 7" tablet within my Atari area, containing all my cart manuals in PDF format. Hence, No original physical Manuals.
- I do try and get decent carts, in decent condition with full undamaged labels.
I have a copy of this http://www.digitpress.com/lists/dplite_atari_2600.pdf as my general games list. I modify the PDF when I get new games, highlighting the relevant checkbox in Acrobat. Prints out on 2 pages back-to-back and good to have in the pocket when game hunting in the wild. If the game isn't on the list, I simply add it in Acrobat.
Also, check out the AtariAge Atari 2600 Top 100 games. http://atariage.com/forums/topic/62626-top-100-2600-games-of-all-time/ Gr8 list of good players to purchase.
Like GeekDragon, I'll have just over 170 when the last purchase arrives
Don't forget to have fun!