help me get KO Propo transmitter batteries

[coolhands]

My old vantage esprit ii takes 2 lots of 4 aa batteries. It totals 9.6v.

It had old nicads soldered into each compartment, which holds 4 on each side ie it has 2 separate compartments.

I need to replace them. Can I go lipo, but if so how? As none are 9.6v. And the prices for all transmitter batteries seem to be ridiculous by the way, even if I buy 4.8v packs of normal rechargeable, like 23 quid etc? seems mad

And ideas please