Naturally, your TGP will do better if it's on paid hosting but they can get an awful amount of traffic. Granted, you're only posting links on your TGP. Still, you'll hopefully get visitors in the tens/hundreds of thousands per day. Say for instance your main page is 50 kilobytes in size. If ten thousand surfers hit just that front page once, that would be 500,000 Megs of transfer or half a gig. Virtual servers charge by gigs used per month. Ten thousand people hitting your TGP just once uses half a gig. You want ten thousand people a day at least for decent TGP traffic and you want them to keep clicking back to your main page a lot.