Matmid (TL) members flying in Economy Class are entitled to store a second piece of baggage up to 23 kilos, in the hold/ For 140 Matmid Club Points (each way).
Do you have AMEX? Not the best use of points but you can transfer MR to El AL and redeem for extra bags?

as mentioned above you can partial redeem for discounts on Duty Free items-most seem to be in your range. Use them now, and then pick up on the flight.
http://www.elal.co.il/ElAlDutyFree/H...e.aspx?lang=en