Actually, they are all the exact same drive! The differences between them are the functions enabled or disabled by firmware.
124,324,524 are all the same thing (you can flash a 124 to 524 fw and get the "bonus" features of the 524)
224,424,624 are all the same as above, but have a lightscribe laser
in other words, grab the cheapest you can find, because you can switch to whatever burner revision you wish