Excel - Please HELP

Im trying to do this for work. 

Im Trying to create a formula that produces a budget amount from a table with a budget code with a corresponding Budget amount. I've used a Vlookup for this. 

I have a general Table where I fill all of the information into. 

I need to create a formula to take the new input [A1 (XXPO_230) B1(Cost: €20)] from budget [G1 (XXPO_230) H2(Value: $30000) and put into C1(The remainder of the PO per each step if (XXPO_230) is used.

If XXPO_123456 with a budget of 20000 is used it will display that value on each step

So say I use budget code  'XXPO_230' for the amount of $1,000 C1; will display €29,000

followed by using the code 'XXPO_230' for the amount of $2,000 C2; will display €27,000

followed down the line by ' XXPO_123456' for the amount of $5,000; C3; should display $15,000

I've attached an excel of what I would like.. If anyone has any advice on this it would be much appreciated!