How much does the text messaging feature cost?

All of the newer phones are 0.3 to send or receive. Some of the older phones have different rates.

Nokia 1112, 2126i
Motorola C139, C261, V176, W175g, W260g, W370, W376g
LG 3280, 1500, CG225, 200C, 300G, 600G
Samsung T101g, T301g
Kyocera K126C
Rate: 0.3 to send, 0.3 to receive.

Nokia 1100, 2600, 3390,
Motorola V170, C155
Rate: 0.3 to send, Free to receive.

Nokia 5100, 1221, 2285, 2126,
Motorola C343, V60, 120
Rate: 0.5 to send, 0.5 to receive.

If you already have a Tracfone you can check the text message rate by entering *#8 at the code entry mode in your prepaid menu.
MO SMS is the send rate
MT SMS is the receive rate