I've talked to a few people on here who say that they would be interested in picking up the TCG if they weren't concerned about the cost of playing the game. And since part of my mission here is to convert more Bulbagarden members into the TCG-fandom like myself, I figure I should dispel a few rumors regarding the cost of playing the Pokémon TCG competitively.
Well, I'll be frank. It costs money. Everything does, these days. However, it's cheaper than you'd think. Unlike a certain heathen game *cough*YUGIOH*cough*, one doesn't need expensive cards to win games, even in a competitive setting.
In Pokémon, the value of cards is often based more on playability than how rare they are. A good example was that Claydol GE (a [now rotated] normal rare!) was, in its heyday, valued much more highly than a number of Lv.Xs, such as Lucario Lv.X MT. (GE and MT are set abbreviations. You'll see me use them a lot.)
So, the most you can expect to pay for a usable card is around $50, for a new-ish, highly playable EX. Sometimes less. Collectable cards, such as first editions, tend to hover a little higher in price, but there's no need to worry about that now. And what's even better is that there are good decks to be built that don't cost much money at all. Garchomp/Altaria looks to be very good in a BW-on format.
The area where most of your money will go is toward trainers and staple cards. Certain trainers and certain Pokémon fit into almost every deck, and they tend to get a bit pricey. However, the good news is that, provided you don't trade them away, you only need to buy them once! No need to buy new staples when you wanna change your deck around! Only the structure Pokémon of the deck need to change. For example, if you want to change your deck from a Garchomp/Altaria to a Hydreigon/Darkrai, the trainers and supporting Pokémon won't change much; just the main lines.
So, for your convenience, I've compiled a short list of staples, how many you should buy/trade for (provided you only want to keep one deck at a time), and approximately what they cost.
Finally updated for BW-on!
4x Professor Juniper - $1/ea
4x Bianca - $1/ea
4x N - $1/ea
4x Cheren - $1/ea
4x Level Ball - $0.50/ea
4x Ultra Ball - $0.50/ea
4x Heavy Ball - $0.25/ea
3x Skyarrow Bridge - $0.50/ea
3x Switch - $0.25/ea
4x PlusPower - $0.25/ea
4x Pokémon Catcher - $9/ea
4x Rare Candy - $1/ea
4x Eviolite - $1/ea
4x Max Potion - $0.75/ea
4x Random Receiver - $1/ea
4x Dark Patch - $1/ea
4x Pokémon Communication - $1/ea
2x Super Rod - $0.75/ea
Aaand... that's about it for staples. There may be some I didn't think of, but if you can get those, you have a good start to any great deck. From there, just decide what you want to run and buy the other necessary components.
So, as you can see, it really doesn't cost that much. After buying the staples, I'd say go to one prerelease every time a set is released and then buy about six or seven packs. Should cost around $50 total, and that's about once every two months. Not bad.
Oh, and events are free. I'm out of time, but I may have more to say on the matter! Comment! Discuss! Inquire!