Making Shruthi-1 or kits

Hi all,
I am new to this site and also Shruthi-1 building so I was hoping to get some advice. Here goes, I have bought 10 x Shruthi-1 pcbs including voice cards and 1 x Shruthi-1XT. I was thinking of building them up to sell on eBay keeping a couple for myself, I have managed to source the components but I am struggling to find the ATMega644p ics already coded I could probably try to do it myself at a push but to find them already flashed would be easier, unless someone could point me to some really good instructions on how to do it?
Also would it be worth putting OLED screens in? it would cost an extra £15 more on each one. I was also thinking of selling some In kit form Do you think that would be a good idea? I have managed to get the outer case in black plastic for them for £15 +/- a few pound I can’t seem to find them cheaper and the metal ones painted white with the wooden end cheeks £60 each I may struggle selling them at that price. Thinking of the price what would be a good price for built up ones and maybe the kits.
Any advice would be greatly appreciated.

It’s not recommended unless you make the required circuit changes to limit the noise on Vcc.

Before you turn this into a business, what about trying to understand first what you’re doing?

That’s what I thought I was doing, I mean I thought that was obvious, but thanks for your input I will definitely take it on board!