if your esc doesn't have a fet lead, i believe you can run the fet lead from the servo direct to your battery to get the 7V.
i've done this with some slower non-fet servos in an effort to increase the performance. it certainly works, but i suppose it's useable life is being compromised by risking premature motor wear.
if the servo is rated for 7 volts, i see no reason that this would be detrimental. as long as there is a signal wire from the receiver for control, it should be fine.
- also, notice on that site that there is a 2113 for $97. i thought it was just a lack of updated status or price, but the part number is different from the special. i'm not sure of whether or not it is a different servo, but something worth noting nonetheless.