The 2313 should be similar in power, it has up to 18 I/O lines instead of 10 and an additional 128B of EEPROM and 2 ADCs, which is two more than the MSP430G2211 and six less than the 2231 [edit: and the TI ADCs might be faster]. But at $2.88 you are being seriously ripped off, I pay 1.10€ at reichelt.de including 19% sales tax, and as far as I can remember, the Euro is still unter US$2.00