I have a 50tc booster, and I've had it for ~4-5 months (I only wanted it for 3, but I didn't know it would auto-renew. (and unfortunately, they're not tradable, or else I would sell it in a heart-beat.)) So it cost me $26. When I originally got it, I was super active ingame, so I thought it would be a good plan, but after about two months, my in-game activity slowed down. The thing is, I only have about 75k earnings from it, so with the $26 I spent, I could've gotten 280k tc instead.

In conclusion, boosters are ok, but only if you play the hell out of toribash and win every match. Otherwise, buy straight tc, it's faster and easier.