VLOOKUP - ARRGHHHH!!!!

This is hard to explain but here goes, a shortened example of my problem

I have created a small table with items 1, 2 & 3 in it with a cost to the right of each. I have Range Named this table TBLA.
I now create another table with the same but Range Name this TBLB
These are my two lookup tables

I now create a third table which has three columns:-

1. I input here, TBLA or TABLB
2. I Input here, 1, 2 or 3
3. Resultant Cost <automatic using vlookup>

My Vlookup in column 3 is as follows:-
=VLOOKUP(B3,TBLA,2) &LT;B3 being my item no.in Col 2>
This works fine but I have to type in manually which table i need the data from.
Is there anyway that the formula will look at Column1 and put in either TBLA or TBLB as it reads it.

Thanks for any advice
Frustrated