Yes, it can be done. To be clear, the tweak is not REDI-specific, and is not elegant, but can be used to insert a cell value into any DDE link, review this Tip On Evaluate via Module to create Module with Eval() code.
Now you can modify DDE example:
1. Create the module with Eval, as shown.
2. Cell B5 contains IBM
C17 contains '=RediLink|'L1'!'
C18 cintains ;LP'
D17 contains =CONCAT(C17,B5,C18)
D18 contains =Eval(D17)
And D18 will ultimately contain your last price, such as:
Let us know if this was of help.