>>52727387feels bad, man
it's not too late to get back into it. The barrier of entry for english cards isn't too high (even though the english sets run for $100 each loose), the e-reader itself is cheap and you can still get lots of cards for fairly reasonable prices.
Here's the tentative pricing list for the premier stuff:
Ruby/Sapphire English:
English RS Freezing Ray + Seizing Poison (blister pack w/ 20 cards): About $100 loose
English RS Hidden Ruins + Cordial Bond (blister pack w/ 20 cards): About $100 loose
English RS Iron Defense + Solid Armor (blister pack w/ 20 cards): About $100 loose
Pokemon Ruby promotional card (Gentleman Nils): $15
Pokemon Sapphire promotional card (Lady Astrid): $15
Eon Ticket (found in both Nintendo Power and promotional E3 leaflet): $200 loose
Australian e-Reader promotional cards (4): Found one e-Reader CIB for $200 but pretty damn rare
Ruby/Sapphire Japan
Japanese RS Series 1 (6 sets, berry card + trainers): negligible (roughly $30 per set?)
Japanese RS Series 1 Collection File: not a card, a binder that was a proof-of-purchase reward, about $200 for a fair price but only shows up in collections
Japanese RS Series 2 (6 sets, berry card + trainers): negligible, but rarer (roughly $30 per set?)
Japanese RS Club Nintendo promotional series (8 cards): Average pricing around $700 for complete set
Japanese e-Reader promotional cards (4): varies, but cheap (easiest promos to find)
Pokémon Scoop (Summer 2003); Pokémon Festa 2003 promo cards (2): little rarer, but still cheap and easy to find
CoroCoro Magazine (October 2003) (Ruin Maniac Sagami): still cheap and findable, many thousands were distributed
"Let's Decorate Secret Bases!" campaign (Japan only) (Regi Dolls Decoration Present) - findable, but steep, a fair price is $200 loose but it's difficult to find by itself (usually included in collections) and can go for upwards of $400
Cool Trainer Mattego (Demo): Never supposed to be distributed. I only know about 3 in existence.